version 11.7.1 new -diag parameters

It appears that -diagDir parameter does not work, at least on AIX

# $DLC/bin/proserve -pf db.pf
OpenEdge Release 11.7.1 as of Wed Jun 14 19:00:30 EDT 2017
16:12:22 BROKER SYSTEM ERROR: Illegal instruction. (47)
16:12:22 BROKER ** Save file named core for analysis by Progress Software Corporation. (439)
Quit(coredump)

/* db.pf */

-diagDir /usr/dbs/dev/logs/diag
-diagPrefix db_name_diag_
-diagEvtLevel 3

The other 2 parameters in .pf work fine.

If we remove -diagDir parameter from .pf file and put it in a command line it works fine.

# $DLC/bin/proserve -pf db.pf -diagDir  /usr/dbs/dev/logs/diag

[2017/07/18@12:15:28.733-0400] P-15466588 T-1 I BROKER 0: (18558) Diagnostic directory (-diagDir): /usr/dbs/dev/logs/diag
[2017/07/18@12:15:28.733-0400] P-15466588 T-1 I BROKER 0: (18576) Diagnostic events value (-diagEvent): LockTable:3,BiThold:3,SysErr:3
[2017/07/18@12:15:28.733-0400] P-15466588 T-1 I BROKER 0: (18560) Diagnostic event level (-diagEvtLevel): 3
[2017/07/18@12:15:28.733-0400] P-15466588 T-1 I BROKER 0: (18561) Diagnostic field separator (-diagFS): ' '
[2017/07/18@12:15:28.733-0400] P-15466588 T-1 I BROKER 0: (18579) Diagnostic data format (-diagFormat): csv
[2017/07/18@12:15:28.733-0400] P-15466588 T-1 I BROKER 0: (18562) Diagnostic pause length (-diagPause): 0
[2017/07/18@12:15:28.733-0400] P-15466588 T-1 I BROKER 0: (18563) Diagnosic prefix value (-diagPrefix): α▌≡

I wonder also why -diagPrefix look different from what I specified, i.e. db_name_diag_