When loading .IT files, two VST instruments I have do not load their parameters unless I click play or if I manually play a note with the VST. They remain on the defaults the VSTs have when loaded into a song for the first time. That is, aurally. Visually, they appear to be set up just how I left them.
It is a problem when using Export as Wave, mainly, as Export as Wave does not cause the parameters to load.
Even if I do play a note or click play, it seems like they still start out from the initial settings, then they transition into the parameters I had set after a couple of seconds, whether it be something manually set up, or a preset.

I tend to close files and re-open them before exporting, to clear out any fading notes, etc. still in the audio buffer.

This problem happens with Rez v3.0 http://www.ugoaudio.com/plug-ins/rez
and SUPERWAVE P8 2.3 http://www.superwavesynths.co.uk/product_p8.htm (2.3 is what it says in the corner in the actual VST, anyway)

Notably, SUPERWAVE P8 1.6 doesn't have this problem.