Hello Andries,
I've experienced that in the past, when i had a very huge local database, and it has always happened when we touched the domain model. For example when we added a boolean or an enum with a default value in an entity with thousands of records, after running locally it was stuck in that point because it was populating all of those rows in the database. Only when it ends, it's ready to run. At the time i was still using the LTS of Mx 8 and the message i think was slightly different, but in any case, you can make a test with this information and test if it's related with this.
Hope it helps,
Rui.