There's a non-standard character L in some cron implementations that stands for "last". it allows schedules like "on the last thursday of the month".

We were happy to discover that Railway's cron scheduler appears to support it - when you set a schedule including L in cron settings, it allows it, and parses the schedule into natural language properly.

However, we quickly noticed that something seems pretty off with it:

• when you try to "apply changes" with such a schedule set, it appears to do nothing, but actually does. you can click "apply changes" infinite times and you don't get any feedback, but when you "discard" the changes you'll discover that it actually DID apply the schedule with the added L.

• while such a schedule is set, everything looks good in the UI - it properly shows the next upcoming execution.

• however, while in this state, manual cron executions triggered via UI just fail with a nondescript error. to trigger a manual execution, we always have to remove the L temporarily, trigger the manual run, and then put it back.

• the actual executions appear inconsistent. we were rolling with this for the greater part of the last year and it generally appeared to work fine, but yesterday for example, it just silently didn't trigger (see screenshot).

would be great to know if this is even supposed to work, or if the actual bug is that it allows the non-standard character in the first place.