Problem with Sorcerer spells and Polymorph

[OMEGA]

Can't figure this out, maybe someone can.

Have Aasimar Sorcerer 10 / Dragon Disciple 1 with base charisma of 21 (+5). i notice when polymorphing with charisma +3 item equiped for 24 cha (+7), I lose 1 spell level 1 and one spell level 5 after each polymorph to normal form.
If I remove +3 item, I notice when polymorph that for 1 second the cha go to 23 (+6), then back to 21 once polymorphed, and return to normal form there is no lost spells.
I put back +3 cha item and when polymorph the cha stays at 24 (21 +3) but when return to normal form, lose spell level 1 and spell level 5 each polymorph.
I have no spell bonus items.

If I remove cha +3 item only in norm form, spellbook lose spell level 3 and spell level 4 each time until zero only.

Why does cha +3 item make it lose spells of all different levels from doing different things? Why not with cha +3 item make cha temp go to 26 and save spells?

[Ariella]

It's to do with the racial modifiers and the fix in place with it. Cast Eagles splendor on your self and changing shape should have no effect on spell slots.

[OMEGA]

Strange fix to me. Okay, does +4 cha item also count? Eagle splendor not spell on my sorcerers list, and scrolls would be dispeled.

[OMEGA]

+4 Item would fix issue same as Eagles splendor? Or must be a spell casting?

TY.