Cannot edit spells in encounter

When selecting a spell to cast and trying to edit something with the spell, it does not let you submit the changes. For example, with flame strike since it does 2 different damage types at 4d6 each, i have been just making it a flat 8d6. Now, it won’t let that happen. It also gives the option to downcast which isn’t really an option since you can’t submit the changes even if you select the correct spell slot level or higher. A work around is selecting either the attack type as melee or ranged and the going back to spell. Doing that makes it work correctly when trying to edit things. Meaning you can edit everything and it shows the correct spell slot levels that the spell can actually use.