I have received this response to my support request from Michel Weststrate. Just in case anyone else has the problem he replied as follows:
I just investigated this issue and I saw that the test project was running on HSQLDB. Your issue is simply solved by switching to a postgres database. HSQLDB is not a realistic test scenario for these kind of cases, because it locks an entire table instead of a single record, which, in this case, causes your app to hang.
I will contact first line support to make sure they add this to their general check list for test projects, so that you get this analysis way quicker the next time. Apologies for that!
I hope that this solves your issue,