First bug, and it's a big one. Damn!
Kits affected: Huntsman of Silvanus, and depending on the circumstances, the Archer, Mystic Marksman, and Spellshafter as well.
Symptoms: Some spellslots will be "un-memorized" each time the game is Saved/Reloaded.
The problem lies in the conflict between the "added" spells and the "subtracted" spells, and only occurs in spell levels where the character has both "added" spells (due to high Wisdom or items that add spellslots) and "subtracted" spells (the spellslot penalties listed in the kit's Disadvantages). Basically, the spell-subtraction penalty is applied first, meaning you lose your spellslots, and then the spell-adding bonus is applied, meaning you get your spellslots back . . . empty.
I didn't think to check for things like this while I was testing, and frankly I have no idea how to fix it at the moment. For now, all I can do is suggest that you do your Saving/Reloading directly before you Rest. Sorry.