Thread prioritization in R28.2

In previous versions of L4T (R27) I’ve been able to easily set the SCHED_FIFO thread priority. On R28.2.1 I get the error:

Operation not permitted

I’ve tried running as root, changing the /etc/security/… files to allow rtprio up to 99, but no luck. I’m setting the priority with pthread_setschedparam() in a c++ application.

Any thoughts on what is different in R28.2.1 that is preventing me from setting thread prioritization?

Below link should be a solution.