Enable Translation Memory - not immediately activated? Bug?

Trados Studio 2021 Beta

We have implemented a TM Provider that impelements ITranslationProviderLanguageDirection.

Scenario

1. Open Project

2. Editor

3. Project Settings

4. Use > Select our TM engine

5. Enable it

6. Close dialog

7. Select other segment

In 2021 Beta, the methods to lookup the segment in ITranslationProviderLanguageDirection are not called. 

In 2019: these methods were called correctly.

Question: did the API change for this particular case?

If we close the file and reopen it, then the lookup works correctly.