I have reported this issue 2 months ago in v3.15. I have downloaded v 3.16 and discovered that this problem has not been fixed yet but readings alt on 1013 and other QNHs works properly now.

Problem sits in request higher/lower alt due to clouds or turbulence when under radar control. Then those options 3,4,5,6 are not showed in PF3 menu but when you will press one of them on blind PF3 responds. Also devil sits in request higher lower alt shortcut H+(1-9) or L+(1-9) this still does not work under radar control.

Logs and screens on attachments.
Let me know if you will need more info