I am experiencing some strange errors and issues working with deliverables in Project Online. I am able to create deliverables, but it seems that after I "sync deliverables" a couple of times, it results in "An internal error occurred" and I am no longer able to save, check-in, or do much of anything with the project. I found and used Allan Rocha's blog, which seems to clear the issue and allow me to continue working with the project - but then, the same issue will happen again. I am thinking it must be something with the stored credentials synchronizing between Microsoft Project and the SharePoint Online site? Has anybody run into this before? Any suggestions for next steps?
