Invalid memory access in nvoglv64.dll due to glPushDebugGroup

I get invalid memory access exception inside one of the nvoglv64 threads. I have tracked it down to using glPushDebugGroup with the message allocated on heap. I even deallocate the message memory after the corresponding glPopDebugGroup. It works fine when the message is in static memory of the program (string literal).
This reference page does not mention any such restrictions.
Am I using it wrong or is this a bug in the driver? I have tried it with 465.89 and 466.27 and both exhibit the same problem.
Thanks for any help.