I should have jumped forward to your last message first instead of working my way through them one at a time and then going of reading about the connection example of the RS485 modules and then trying to decode the protocol only to find you have already done it. LOL
Glad your getting consistent and predictable results now and look forward to you posting the project is finished and working as expected. Also glad to help though I don't feel I helped much apart from showing someone was listening.
I would like to investigate the old MAX485 modules in more detail as I feel the boards you bought are probably just the same as the rest of them that look the same (like mine) but maybe they have faulty MAX485 chips or some other issue.