Found a working answer from 2022:
https://ttlc.intuit.com/community/after-you-file/discussion/re-where-do-i-incorporate-my-california-...
It's a very old problem in TurboTax Business that Intuit hasn't fixed. Specifically, in addition to filling the K-1 and 3804 worksheets, I had to manually enter it into 100s:
5. Open Form 100S p4-6 and scroll down to Credits Line 13d. Enter a description for the PTE Tax Credit from Form 3804 and the total amount in the middle column. This step will allocate the tax credit to all Schedules K-1.
