BLFs for Time Conditions randomly stop updating

The BLFs for time conditions randomly stop updating.  Per an old thread in the forums I had done some troubleshooting and noted that when they have stopped working that the schedtc line is not being written into asterisk's crontab. 

Last time this happened I ran /var/lib/asterisk/bin/schedtc.php --debug  the schedtc line appeared again in crontab and they worked for approx. 14 days before stopping overnight last night.

I confirmed that schedtc was again missing from crontab.  Ran schedtc again manually as above and the BLFs immediately updated and started working and the crontab once again contained schedtc

[root@fpbx01 ~]# crontab -l -u asterisk | grep schedtc

[root@fpbx01 ~]# /var/lib/asterisk/bin/schedtc.php --debug
Time Now:08:30|Mon|5|Nov|America/Edmonton==Working with TimeCondition:StarMANIA Open/Closed==
INVERTED BLF: false (NOT_INUSE = NOT_INUSE & INUSE = INUSE)
OVERRIDE MODE: not set
=>08:00-17:00|mon-fri|| is now
TIME MATCHED: True (NOT_INUSE)
BLF MODE: True (NOT_INUSE)
Privilege: Command
Changing TC9 to NOT_INUSE
==Working with TimeCondition:IUL Open/Closed==
INVERTED BLF: false (NOT_INUSE = NOT_INUSE & INUSE = INUSE)
OVERRIDE MODE: not set
=>08:00-17:00|mon-fri|| is now
TIME MATCHED: True (NOT_INUSE)
BLF MODE: True (NOT_INUSE)
Privilege: Command
Changing TC8 to NOT_INUSE

[root@fpbx01 ~]# crontab -l -u asterisk | grep schedtc
* * * * * [ -x /var/lib/asterisk/bin/schedtc.php ] && /var/lib/asterisk/bin/schedtc.php

[root@fpbx01 ~]#