I’ve already reported the issue in another thread. However it has been ignored. It affects the PC version of all Plugins that use VSTGUI 4.9 and use fractional zoom factors. It also seems to affect JUCE.
The GUI remains black or closed when setZoomFactor is called within createView(…).
It appears when GUI width and height is not divdeable by the scaling.
Example: calling setZoomfactor(1.75) does work when the GUI has the size 100 x 100 (1.75 x 100 = 175). It does not work with 99 x 99 (99 x 1.75 = 173.25)
To make things even worse it also appears when setContentScaleFactor is called from the host. Some hosts (FL Studio, Bitwig) do call it with a value of 1.25. As a result the GUI of many plugin remains black.
The issue is also reproducible with the default VST SDK examples.