Repository settings in optional extended integration with e.g. Bitbucket Server are not persisted

With the latest Windows build 3.3.9 the integration with my local Bitbucket Server account is not persisted in the repositories and e.g. checking out branches via Bitbucket Server always causes problems because the optional extended integration options for a repository are not saved.

Steps to reproduce:
1. Change respository extended settings from a the Standard to Bitbucket Server
2. Save changes and close Sourcetree
3. Open Sourcetree again and verify the extended settings are stored