Question

I have s1 pro. The stock plugins all open fine, and until I most recently opened the program, so did the third party vsts. Now they still show up but don't open?

Answer 1

Sorry, this is not an answer but sounds somewhat related

I only experience this with Analog Lab 3. I run Windows 10 (1803) which is certainly buggy itself

If I drag it onto an existing song, nothing happens..

If I try to replace an existing VI it forces the original vi to disappear but never populates so the track becomes blank

If I instanciate AL3 on a new song first it works but about 50% of all other plugins now react like AL3 above.

AL3 is the current v3.2.0.1509 and it still happens on S1V4.01