While I was flippant and presumptuous in my post, the meat of it holds true.
We use afollow when we detect a nav mesh isn't loaded, if you are close enough that we think it will work.
The warning is new, and was mainly aimed at people using the follow me button and not knowing any better... however, it holds true even if we are falling back to it (which is not new). It isn't ideal for RGMercs.
I would verify that the mesh is loaded, if you have not... We can go from there.