No need to apologise...I do so appreciate your time and your expertise.
Please forgive the time it's taken me to respond....it's been a long day at work.
It seems this issue has us both a little bemused. It is indeed strange that the panning issue didn't occur on your machine despite the presence of the controller info. I did think about the Surround Sound option having an effect, and I have now turned it off. However it seems that any project with it initialised at the projects inception continues to require it's operation. For future projects I shall disable it and opt for stereo.
I don't think that the issue is with the Portal or Thermal plugins for two reasons. Firstly, I acquired them both very recently and the panning issue was happening before I got them, and secondly, I received them both from a music producer friend of mine, who uses an almost identical set up to mine, and he has had no issues.
I did realise [eventually!] that I needed to delete the panning info in the Event Editor for each of the regions, and having done this it did help to a degree, although there is still a bias towards the left of the stereo field on playback.
Hopefully opting for Stereo rather than Surround Sound will clear the issue in a new project, although it seems strange that the Surround Sound would give this kind of panning information to such specific drum sounds from the Producer Kits.
In a way I'm glad that this has you baffled too as it has perplexed me for some time.
I cannot thank you enough for your time and energy in giving me your assistance to try and figure this out. I have been most impressed by not only your expertise and your patience, but also with your kindness, and I am truly grateful to you and I am in your debt.
Wishing you all the best in all your endeavours
Dom