We have several legal entities (A, k, C,...) and cross-company sharing activated for customers and vendors. If you create a new vendor in one legal entity (A), D365 will automatically create the same vendor in K, but the sales tax group is missing. Sales tax group is not shared and basically initialized by the setup of the vendor group. This works for the first legal entity (A) where you create the vendor. As soon as you create the vendor the sales tax group will be defaulted based on the setup of the vendor group. This doesn't work for all other legal entities where the new vendor will be copied.
This leads to errors if you want to update vendor data (in K) via Power Automate, because the record is not editable as long as the required fields (sales tax group) are not filled.

Possible solution: While creating vendor data in other legal entities the same business logic (like creating it manually) should be used. -> initialize the sales tax group based on the vendor group.