I've seen this issue a couple of times and I'm not sure what's causing it.
When I went to enter a new transaction, I get code in the Category dropdown
QuoteC{{$parent.$parent.$parent.getCategoryBalance(category.id)...
as well as the category for the currents month income not displaying a month (see attachment).
I am unsure if it happened this way the other times I've encountered this, but at least this time, it occurred after entering a new Payee and pressing <tab> to switch to the category field. A secondary "bug" here is that when I enter a new Payee, pressing <enter> does not save the Payee and move to the next field as expected.
I can't seem to recreate it consistently, but it also might have something to do with entering an unexpected date format in the transaction?
I'll fix this later today. Thanks for reporting!