Child processes stuck in R status

I'm wondering if anyone has seen this and/or how it is even possible.

We're having some issues that at least on the surface look like a
slowloris attack or variant; on the server-status page multiple child
processes appear to be stuck in R status with large seconds-since
values. But I don't think it's an actual attack for two reasons: the
URLs being accessed (again from the server-status page) are reasonable/
typical URLs that we'd expect from our users and processes (including
some that are not externally published and used only by internal
scripts); and all (well, most) of the IP addresses in the list are from
known, trusted users.

Also, we do have (and have had) slowloris mitigations in place and for
the most part (this issue notwithstanding) they seem to be working as
expected.

More confusing, when I look in my access log I see the same hits 
appearing in R status on the server-status page ALREADY having been 
logged. As if Apache responded to the request (typically in 
milliseconds, which is as expected based on the requests being made), 
logged the hit in the access log, but then for some reason left the 
request in R status (?)

Is there any way that's even supposed to be possible? Or perhaps the
child moved on to the next request, but somehow got stuck at a point
before the URL posted on the server-status page was cleared (so it's
actually reporting the previous request's URL, even though it's in R
status)?

Any help/pointers would be appreciated.

Thank you!

Dan