Thanks for everyone chipping in here…
I am very time poor at the moment and cannot take the website down to test every single plugin 🙁
However I re-instated the previous version of Events Manager and every thing is working again.
My deduction here is that it is not any other plugin, but an issue with the latest update.
Sorry I can’t help more than that, the silly season is here, and things are quite crazy.
The version is Version 5.5.4
Thanks
After more checking, the calendar events for this month also disappear if you click on the forward arrow (to next month) and then back again to this month.
Thanks.