So it is.
Well in that case all those RN CVEs without air groups are useful only for replenshiment TFs; when they load supply points on formation of the TF they are loading replacement aircraft out of the pool which then go into the air groups of a replenishing air combat TF. The only other use is transporting land based air groups, but by the time you get them most allied aircraft have the range to base hop to where you need them.
I haven't played Pacwar for a few years, but don't recall a problem with the RN CVEs with assigned air groups flying; I used to always play the whole war though, not the later start scenarios, in which a lot of lost allied units have been deleted from the database and things moved around.
Have a look at the groups' data with pacedit if you have it and see if there's a problem with the type of planes on board - only certain data lines in the aircraft database are hardwired for carrier capability. There are also a number of air group data slots that were hardwired to certain ship data slots, and any scenario edits had to adhere to those. I made a list of them 20 years ago, can't find it now, but basically they cement the historical IJN and allied carrier airgroups from the original campaign scenario carriers to those ships and cannot be used for anything else, although other air group data slots can be used on other (and those) ships and work if you use carrier capable aircraft in the group.
"You may find that having is not so nearly pleasing a thing as wanting. It is not logical, but it is often true."
- Cdr Spock