No outline for one sqlrpgle source in RDi 9.1

This one defies explanation - so far at least. On occasion, I need to browse a source member from one of our production libraries, and for this member only (as far as I've encountered), I can't get an outline.
What makes it most peculiar is that I can copy that source to a source file in my own library, and the outline is fine.

Sometimes I can find the cause by running the verifier, but in this case, the verifier only shows two sev 20 errors that are bogus: "Keywords DFTACTGRP, ACTGRP, or USRPRF are not allowed." (I get this routinely in v9.1 from the verifier for SQLRPGLE members that compile fine).

I thought it might be something about that production source file, but I get outlines for other sqlrpgle members there.

So, I'm at a loss. My workaround is to just have a source in my own source file, but when I need to traverse it with the SEP debugger, that requires that I have an object from that source in the runtime library list too. This one is a "relic", with a big mainline, a bunch of subroutines, mixed with some subprocedures and free-form code. The Outline is really helpful, when I can get it.

My next solution is to upgrade to 9.5, but I can't just yet. Soon. In the meantime, perhaps someone has a suggestion for where I should look to find the real reason?

Many thanks,
Michael Koester