Can't put server into MAINT mod -- automatically put back into service

Help!
1

I am running HAProxy version 1.5.2.
Using the stats GUI when I try to put a server in to MAINT mode it immediately reverts to being in service.
Message in the haproxy log looks like this:

Jan 23 10:01:07 Server blahblah is going DOWN for maintenance. 8 active and 1 backup servers left. 0 sessions active, 0 requeued, 0 remaining in queue.
Jan 23 10:01:07 Server blahblah is UP/READY (leaving forced maintenance).

Same procedure on HAProxy 1.6.2 works as expected. haproxy.conf looks the same on both versions so I suspect perhaps a problem with the version but I can’t find any specific notice about this. Anyone else run into this?

2

Please use the latest bugfix release from haproxy.org.

v1.5.2 contains 201 fixed bugs, 117 of them considered MEDIUM or MAJOR.
v1.6.2 contains 185 fixed bugs, 94 of them considered MEDIUM or MAJOR.

Not sure what is causing your specific issue, but you should upgrade in both cases.