Without any details about the project, how you’re using pluskit there’s probably not much that can be said other than the most generic things:
a lot of options changed in PlusKit 4 – most specifically to add specific enables/disables for specific page types and features of PlusKit. this allows you to only enable the features that you need for any specific project – this makes PlusKit run much faster and is less prone to incompatibilities. those are all good things – but it also means that if you should probably take a look at those enable switches and make sure that the ones that you need are turned on.
some enables are switched off by default – this is because they’re in the “not recommended” category – specifically an import between page types that tend to be more prone to errors and incompatibilities.
if that’s the case you can try switching it back on – if it has worked in the past then it probably should continue to work. but i’d also recommend taking a minute to consider that you’re off the beaten path and perhaps there might be another more straightforward method to do the things that you’re currently using pluskit to do.
if that’s not it at all… if you have everything enabled and pluskit still isn’t doing it’s job, then send the project file (along with any other themes/addons/stacks/whatever that we’ll need to open it – these files are all very large so you’ll probably need to zip up the project file and share it via Dropbox or another similar service) to YourHead support and we’ll have a look. With the project file in hand we’ll be able to tell you exactly what’s going on and what we can do about it.