Hi Frank,
I also have a Tyros4, and as you say there is a problem with the effects on some styles that have originated from later keyboards such as T5, PSR-S970 and Genos.
I have found that many of the styles which exhibit this problem use the 'Hall 1' DSP for the system reverb.
I found that if you open the 'Mixing Console' (I usually open it at the 'Panel Voice' page but I think that you can open it on the 'Style' page too) and move to the 'Effect' tab, then select the 'Reverb' row (B or G button) and press 'Type' (button F).
This will open the DSP selection screen and the current DSP type used for the system Reverb will be highlighted. As I said this is often 'Hall 1' on styles which have this problem.
If you now use the #7 or 8 button pairs to move off the current DSP Type selection, and then move back to the original ('Hall 1'), the reverb should be restored.
If you return to the previous screen and while playing one of the parts, adjust the reverb level for it, you should now hear the effect alter as you adjust it., unlike before modification, where the sound remains the same whatever level Reverb is set for that part, or any other for that matter!
The good news is that simply adjusting one part as above seems to 'reset' the reverb for all parts, in all style sections, but once you have done it, you must save the style from within 'Style Creator' to keep the changes.
The bad news is that you need to do this for each style that has this 'problem'!
I noticed this years ago and mentioned it once in a post to this forum, but I can't remember anyone else asking about the problem. I'm pretty 'cloth eared' but it was obvious to me from the first time that I heard it that the effects on such styles weren't sounding correctly on my T4!
It makes me wonder how many people are using these 'dry' styles on their keyboards without realising that there is no system reverb applied!
Regards
Ian