I can't get region effects to engage most of the time. I highlight a section or an entire track, select region effects, and then nothing. I can't get them to engage. My selected audio can be processed in every other way but region effects won't kick in 95% of the time.
 
The audio clips are as recorded. They have not been bounced or converted to groove clips.

Hi. I do not know if this is of use to you, or if you have done this already, but try splitting the section you want to use region fx on. I have not tried to just select part of a clip to use region fx on.
All the best.

It also might help if you bounce the clips to themselves before engaging Region Fx

Bristol_Jonesey
It also might help if you bounce the clips to themselves before engaging Region Fx

+1
I always bounce to clips before using region FX.

Thanks for the ideas, I'm going to look into each of them. I didn't think region effects would work on groove clips but I'll give it a try. One thing I accidently stumbled upon is is a switch in the Pro Channel Clip sub menu. There is a switch that enables audio snap and it always seems to be enabled in my projects. If I turn it off then I can apply region effects. Enable it and no region effects are available.

John, nobody suggested converting them to groove clips - in any case, bouncing a clip to itself will remove it's "grooviness" and also any AS information.
 
It's a good precursor for setting up any Region Fx successfully

ampfixer
...There is a switch that enables audio snap and it always seems to be enabled in my projects. If I turn it off then I can apply region effects. Enable it and no region effects are available.

Correct - both Groove Clips and AudioSnap, in addition to Region FX, are exclusive.   IOW, you can only have one of those options active at a time on any given clip, since they all can affect timing.  
 
It sounds like maybe you're using a template where AS is active?   I'm not sure if that's even possible (?) but it seems that way...

Having AS enabled on all projects would be a very quick way to piss me off royally.
 
As Steve suggests, check your templates to see what's going on.

It seems that AS selected in all my templates was the culprit. Don't know how I did it, but it's fixed. Thanks for all the help.

Cool!   Everyone loves a happy ending.