Snap is updating off schedule

Here’s the latest data starting just after the last post.
Monday 6:27 AM
$ snap refresh --time
timer: 21:00-22:00
last: yesterday at 06:25 EST
next: yesterday at 21:00 EST

Monday 3:02 PM
$ snap refresh --time
timer: 21:00-22:00
last: today at 11:33 EST
next: today at 21:00 EST

Tuesday 9:29 AM
$ snap refresh --time
timer: 21:00-22:00
last: today at 08:48
next: today at 21:00 EST

Wednesday 11:01 AM
$ snap refresh --time
timer: 21:00-22:00
last: yesterday at 21:22 EST
next: today at 21:00 EST

Thursday 5:33 AM
$ snap refresh --time
timer: 21:00-22:00
last: yesterday at 23:54 EST
next: today at 21:00 EST

Thursday 3:37 PM
$ snap refresh --time
timer: 21:00-22:00
last: yesterday at 23:54 EST
next: today at 21:00 EST

Friday 6:43 AM
$ snap refresh --time
timer: 21:00-22:00
last: 2 days ago, at 23:54 EST
next: yesterday at 21:00 EST

Friday 5:56 PM
$ snap refresh --time
timer: 21:00-22:00
last: today at 16:37 EST
next: today at 21:00 EST

Sunday 7:54 AM
$ snap refresh --time
timer: 21:00-22:00
last: yesterday at 06:04 EST
next: yesterday at 21:00 EST

Monday 7:43 AM
$ snap refresh --time
timer: 21:00-22:00
last: yesterday at 11:57 EST
next: yesterday at 21:00 EST

Monday 4:28 PM
$ snap refresh --time
timer: 21:00-22:00
last: today at 16:08 EST
next: today at 21:00 EST

Tuesday 9:58 AM
$ snap refresh --time
timer: 21:00-22:00
last: today at 07:17 EST
next: today at 21:00 EST

$ journalctl -u snapd.service |grep autorefresh.go | tail -n 20
Feb 10 11:33:34 Books snapd[1004]: autorefresh.go:397: auto-refresh: all snaps are up-to-date
Feb 10 11:38:32 Books snapd[1004]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-10T21:00:00-05:00.
Feb 11 08:53:28 Books snapd[23417]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-11T21:00:00-05:00.
Feb 11 16:51:57 Books snapd[1052]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-11T21:00:00-05:00.
Feb 11 21:22:40 Books snapd[1052]: autorefresh.go:397: auto-refresh: all snaps are up-to-date
Feb 11 21:27:38 Books snapd[1052]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-12T21:00:00-05:00.
Feb 12 10:51:23 Books snapd[1039]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-12T21:00:00-05:00.
Feb 12 23:54:11 Books snapd[1039]: autorefresh.go:397: auto-refresh: all snaps are up-to-date
Feb 12 23:59:08 Books snapd[1039]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-13T21:00:00-05:00.
Feb 14 16:37:08 Books snapd[1039]: autorefresh.go:397: auto-refresh: all snaps are up-to-date
Feb 14 16:37:08 Books snapd[1039]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-14T21:00:00-05:00.
Feb 14 17:03:41 Books snapd[963]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-14T21:00:00-05:00.
Feb 15 06:04:37 Books snapd[963]: autorefresh.go:397: auto-refresh: all snaps are up-to-date
Feb 15 06:09:34 Books snapd[963]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-15T21:00:00-05:00.
Feb 16 11:57:49 Books snapd[963]: autorefresh.go:397: auto-refresh: all snaps are up-to-date
Feb 16 11:57:49 Books snapd[963]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-16T21:00:00-05:00.
Feb 17 16:08:17 Books snapd[963]: autorefresh.go:397: auto-refresh: all snaps are up-to-date
Feb 17 16:13:14 Books snapd[963]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-17T21:00:00-05:00.
Feb 18 07:17:56 Books snapd[963]: autorefresh.go:397: auto-refresh: all snaps are up-to-date
Feb 18 07:22:53 Books snapd[963]: autorefresh.go:253: DEBUG: Next refresh scheduled for 2020-02-18T21:00:00-05:00.

I hope this helps