What was the “oldest” FW version you tried?
All my boards run FW 3.65 (vesc-tool 1.28) because it works flawlessly.
I had many dangerous troubles with FW 4+ so no thanks.
I would try it with FW 3.65 (vesc-tool 1.28), if the locking at full speed still exists then probably your esc’s are faulty.