Would AL DMs Allow Conjure Minor Elementals cast with 7th Level Slots to have the 6th level slot effect?

Question

Conjure Minor Elementals (Basic Rules) and similar spells have the following text at the end of the spell block. My D&d Beyond account says it comes from Basic Rules, pg. 226, and AFAIK there's not any updated versions.

At Higher Levels. When you cast this spell using certain higher-level spell slots [...] more creatures appear: twice as many with a 6th-level slot and three times as many with an 8th-level slot.

Following a very literal reading, there seems to be a weird edge case: a 7th (or 9th) level slot is not one of the "certain higher-level spell slots" listed in the spell description, and thus would have no benefit vs. casting it at the lowest possible level.

This is extremely surprising to me, because I can't think of any other situations where a higher level spell slot (7) produces a weaker effect compared to a lower level spell slot (6) when casting the same spell. I have a feeling this can't be intended, but I can't find any official rules or rulings that would support the idea that casting using a 7th level slot should allow the Druid to summon additional creatures as if he used a 6th level slot. I have carefully reviewed the rules for Spellcasting including Spell Slots and Casting a Spell at a Higher Level to see if a general rule might allow a higher level slot to replicate the effect of a lower level slot, as well as looked for specific errata or Sage Advice for this Spell and come up blank.

AL DMs also have less leeway than most DMs for adjudicating situations according to "Rule of Cool" or "Rules as Intended". The D&D Adventers League Forgotten Realms DM's Guide says

You can issue rulings to your table when the rules of the game are ambiguous or vague, but you must otherwise adhere to the rules as they are provided in the core rulebooks and can’t change them or make up your own; “house-rules” aren’t permitted for use.

While they aren’t official rules that must be followed, the Sage Advice column, tweets from the D&D Team on Twitter, or even discussions with other DMs on your favorite social media platform can provide good insight on how others adjudicated a particular issue

As I'm planning to run a druid in AL for the first time starting soon, I'm interested in knowing if I have to make sure to keep exactly a 6th or 8th level slot available to gain benefits from casting these spells at higher levels, or if 7th and 9th level slots would work as well.

I don't think any official rulings exist, so I'm mostly hoping to get an answer that is based on experience in AL play, but in case I missed something, I prefer answers higher on this priority list to lower:

1. Answers such as "Yes, in AL play you can gain the 6th level effect when using a 7th level slot" (or "No You can't [...]") because of a general rule I missed that covers this specific case.
2. "Yes, you can [...]" or "No you can't [...]" because an updated version of the spell or general spell casting rules was published in [Name of Source Book], Errata, or the D&D Adventurer's League FAQ.
3. Answers such as "Yes, you can [...]" or "No you can't [...]" because the situation was clarified in Sage Advice.
4. Answers such as "Yes, you can [...]" or "No you can't [...]" based on tweets from the D&D Team on Twitter.
5. Answers such as "Yes, you can [...]" or "No, you can't [...]" based on direct experience in AL play with how DMs have adjudicated this specific spell, or other spells following the same pattern (conjure woodland beings, etc.)
6. Answers such as "Yes, you probably can [...]" or "No, you probably can't [...]" based on general observed trends in AL play with how literally DMs in AL play interpret rules vs. acting as a "Facilitator of Fun" or trying to apply RAI.

Answer 1

When it is spelled out, those specific options exist.

The spell says that you can cast it in its correct slot (4th) as well as two specific effects for using higher level slots: 6th and 8th.

Casting in a higher slot

The basic rules for Casting a Spell at a Higher Level (p.201) are relevant:

When a spellcaster casts a spell using a slot that is of a higher level than the spell, the spell assumes the higher level for that casting. [...]

Effectively, the spell expands to fill the slot it is put into.

Some spells, such as magic missile and cure wounds, have more powerful effects when cast at a higher level, as detailed in a spell's description.

We also know you are allowed to slot a spell into a higher level slot without changes.

Conclusion

Our spell in question is 4th level, it has a specified effect that is independent of the spell level. Casting in 5th level slot does not alter the effect. In a 6th level slot, the effect is specified to double, in 8th it is told that it triples. Nothing is spelled out for 7th or 9th-level slots.

This allows the GM to adjudicate in two versions:

• 7th and 9th level slots default to the base 4th level version of the spell.
• 7th and 9th default to their next lower-level variant of the spell, in this case, 6th and 8th.

The 2nd ruling would differ from the rules as written, which only dictate alternate effects for 6th and 8th level slots, and thus is banned by AL - so the 1st ruling has to apply.