I was using 8.3.2p4 (now p9). It's been working without any issues. If it kicked off last night check the policy again that uses that schedule. Looks like your cron schedule is correct, but maybe not applied right on the snapshot policy.
Here's what my config looks like.
The SysMgr GUI for the Monthly schedule (created under Cluster>Configuration>Schedules) shows this:
Runs at:
Months: January, February, March, April, May, June, July, August, September, October, November, December
Days: 1st day
Hours: 12 AM
Minutes: 15th minute
Here's the cron schedule for the Monthly schedule from the CLI
ontapcluster1::> schedule cron show *Monthly*
(job schedule cron show)
Name Description
---------------- -----------------------------------------------------
Monthly Jan-Dec 1@0:15
Here's the snapshot policy applied to the volumes I tested from the CLI
ontapcluster1::> volume snapshot policy show -vserver ontapsvm1
Vserver: ontapsvm1
Number of Is
Policy Name Schedules Enabled Comment
------------------------ --------- ------- ----------------------------------
SVM_Daily14_Weekly6_Monthly12 3 true -
Schedule Count Prefix SnapMirror Label
---------------------- ----- ---------------------- -------------------
Daily 14 Daily Daily
Weekly 6 Weekly Weekly
Monthly 12 Monthly Monthly