IDE Form tabs missing


Getting some odd behaviour in the IDE: Not all the tabs are showing.
I have 3 forms which show in the Project Explorer but I cannot access all the forms or code because one or more do not have the corresponding tab in the main area. Clicking on the form in the explorer selects the visible ones but does not load the missing one.
I have tried resetting the IDE, unloading and reloading and two different PCs.(x32 & x64). The project was fine when saved and shut-down.

Older versions usually load back OK but sometimes they have a tab missing. This has happened a few times and must have an underlying cause.
Is there a setting or workaround somewhere that I’ve missed.


I have never seen this, nor have we had other reports. Does it happen with just one project or others as well?


I’m only working on the one project as I’m a new user.
However, it has happened with different copies of the same project.
Would it help if I sent you the zipped project file to see if it reproduces with you?


Is there a sequence of operations which shows the problem 100% of the time?


Unfortunately, not that I am aware of (although logic suggests there must be) - it just sometimes happens.
The only other effect that seems to be associated is that the components on the form become locked in some way (if I remember correctly) - they show but cannot be ‘selected’. After that, the form itself becomes inaccessible.
I have a saved project with the form visible in explorer but not in the window,