Every month starting January 22 @ 6pm sets a reminder for 1/22 @11:59pm
This is an incorrect due date formula. A task with a due time requires the due date of the task itself to have a time and not the starting date.
That said, the correct format is:
every month @ 6pm starting Jan 22
however, in case of a monthly recurring task, we strongly recommend to use this much simpler format:
every 22 @ 6pm
every 22 @ 6pm starting Jan 22
but the second form is currently not required as if you don't use a starting date, Todoist will assume it to be the next available 22nd which will be in January.