Using 5.10.2 but this issue goes back many versions prior.
I've tested various assigned automation parameters with Gig Performer 5 and Reaper 7, and there are all sorts of issues with the parameters either not responding at all to host controls, not responding properly to host controls, and/or not retaining values set by host controls. VST and VST3 are affected the same way, so please look into how these plugins are handling reporting their state to the host when automation parameters have been assigned.
