"This item has been removed from the calendar" error losing changes to notes for tasks

Love eM Client, but I have a small problem. I often have tasks open for a while because I have quite a few notes associated with some of them. However every now and then the task comes up with the following error while it is open:

“This item has been removed from the calendar. The form will be closed and all the current changes will be lost.”

Is there a workaround or fix as I keep losing my notes.