I have a VBA project with several userforms and modules that's evolved over many years. As of today, PowerPoint 2016 on Windows fails to load the pptm project without error and I've tracked it down to one userform in which all of its ~20 controls except one (a MultiPage control) have disappeared and hence the numerous corresponding control events code, which is still present, is complaining.
When I open the project in PowerPoint 2013 or 2010 the userform appears correctly and the project compiles. I have exported the userform from 2010, deleted it from the project in 2016 and re-imported it into the project in 2016. The userform still appears to be empty apart from the one MultiPage control and the project doesn't compile.
This userform isn't the only one using a MultiPage control so I don't think that's the issue. If I remove the userform from the project and the associated .Show method elsewhere, the project compiles normally.
What is going on?!
PowerPoint 2016 PC version 1806 build 10205.20009