Adding a new entry to the translation provider settings yields error "When setting PerformUpdate to true, PerformNormalSearch should also be true."

Trying to add a new TM to the list of translation providers in a Studio project yields the error "When setting PerformUpdate to true, PerformNormalSearch should also be true."

Fact is, that one of the TMs (not the one that I want to add but one that already exists) is set to Lookup = False and Update = True in the project settings prior to adding a new TM to the list of TMs. The UI accepts that configuration without any issues.

Now, using the code below, I want to add a new TM to the list. When save my config, I get the above error. The error does not occur when I set all TMs to Lookup=True before running the code.

Is there a known limitation with respect to that using the API?

Many thanks for a quick reply.

Tom