I installed Max 5.1.6 the other day, (the day before a concert - silly me) - assuming everything would work, but when I loaded some of my patches that have VST plugins with fxp presets that load at startup, all the controls of the VSTs were set to their minimum on every plugin. This of course rendered these patches unusable and I had to quickly reinstall 5.1.5 before the show. That fixed it - presets loaded normally again. I didn't have time to test more, but maybe I will later today.
Anyone else have this issue? Seems to me like it could be a bug in 5.1.6 since all I had to do to fix it was reinstall 5.1.5.