Just FYI,
Region FX have restrictions on them (at the bottom of that page), and you hit on one of a few. You need to bounce to exit "Region FX" mode to enable any of the below:
"Region FX clip restrictions
The following editing functions are disabled for Region FX clips:
* Clip automation.
* Copy/paste for a time selection that contains a Region FX.
* Split clip.
* Slip-stretch clip when the Follow Host Tempo option is enabled.
* Groove Clip looping.
* AudioSnap."