@UWPVIOLATOR once all nodes are at 1.5.5 I don’t imagine there being an issue with updating nodes as needed. 1.5.5 the logic for replication changed quite a lot which is why we highly suggest making sure all nodes are at least st this level first.
Mind you reasoning:
Logic checks occur at the nodes themselves, so 1.5.5 modified how these checks operated.
Master checks changed and need the information returned in such a way that only 1.5.5 did properly.
I’m sure there’s more but this is more to just illustrate the point more directly as to the “why”