mike841 wrote: how could MPC v1.9 and v2.1 open a project that v2.10 could not?
This troubleshooting info would have been something useful to share in the original post.
If the project is working in 2.1, why are you still trying to load the original 1.7 project? Save a copy of the project in 2.1, or whatever the newest version of the MPC Software is that will load it and use that newer version for your troubleshooting.
But most likely Akai have changed the way they handle VSTs in 2.10 which is why the project is working in other versions. They might have tweaked something to accommodate one plugin and this has caused problems with other plugins. Have you tried starting a fresh new project in 2.10 in Windows 10 and loading some of these plugins into that project. Are the plugins up to date? Legit or cracks?
VSTs are a problem as they are created by third parties, Akai cannot control any aspect of the VST. Which is why I'm surprised they refunded you, certainly not before making you rule out any issues with the plugins (i.e. as per my recommendation to disable the plugin programs before loading).