Yeah, wallet funds are fairly inflexible. You can't even use them to upfare, unless the ticket rules allow for a full wallet refund, then re-issue an entire new ticket in the new fare class using whatever funds you have.

I wish they would just treat it like an Alaska gift card. Anywhere Alaska accepts cash (tickets, lounge membership or food, fees like bags or changes, on-board food/drinks) you should be able to use Wallet funds. I get why they don't (mainly an accounting and regulatory nightmare) but it sure would be nice.