Front Panel refuses to Close in EDIT mode

[CoastalMaineBird]

LV 2018 SP1,  Win 7  

I have certain VIs which occasionally refuse to close their front panels.

Please note that I am NOT talking about code, I am referring to EDIT mode.

Clicking the [X] doesn't close it.

Choosing Ctrl-W doesn't close it.

Choosing FILE | CLOSE doesn't close it.

It remains in the WINDOWS list.

I can still EDIT it.  It's not still running.

I can SAVE it.  I can OPEN / CLOSE the diagram window.

Other windows in the same project are unaffected.

It happens on different windows in different projects, but it is ALWAYS on a reentrant-VI with clones involved.

I have to CLOSE ALL from the project, or close the project itself before it disappears.

If I close the project and re-open, it won't happen, until I edit the master VI.  Then it (maybe) will happen.

Is there a DON'T BE STOOPID setting in the INI file I am missing?

Should I always close ALL the clones before I edit the master?

Any ideas?

[Coddiwomple]

It seems this is a recurrent issue that has been discussed to no avail thus far. Perhaps someone has figured it out since the last post for the same issue. Sorry for the frustration it causes. 

See original thread here: LabVIEW front panel of reentrant VI doesn't close (in edit mode) - NI Community