It looks like most probably due to coronavirus Loganair have taken flights off sale on the Glasgow route for March, April and May. They are as follows.
Wednesday 18/3/20, Wednesday 25/3/20, Tuesday 31/3/20, Tuesday 7/4/20, Wednesday 15/4/20, Monday 20/4/20, Tuesday 28/4/20. Looks like there will be no flights on Tuesdays and Wednesdays in May. It also looks like during April and May some of the 20.50 departures on Fridays and the 11.05 departures on Sundays have been taken offsale or are marked as sold out. It looks like the schedule gets back to normal in June.
Edinburgh looks unaffected so far.