I created a world in the affected versions mentioned above, to check for another bug that I had discovered (MC-151181) and I found a block of water that was still, even with space around it. I removed it and then I placed it back. It started flowing properly. This generation bug didn't happen in Minecraft 1.14.1 Pre-Release 1. It stayed still for a bit, then it started flowing properly.

Steps to reproduce:

1) Create a default world in the affected versions mentioned above with the seed 8689861349976835674.

2) Look at your right. You will see a farm of a savanna village.

3) Go there. You will find a block of water with space around it not flowing properly.