I am having the same issue with importing PIT into Showcase.
We have two computer with Showcase 2014. One of them import IPT just fine, the other one fail on the same file.
I have not be able to find any difference in the settings or preference.
It is a time consuming process for us to export to STEP file or DWG first, as there often are adjustment to our models, and if the person updating the part forget to export a Step file, there is no indication in Showcase that the files has been updated. And with 5.000 products it has proven had to keep track of updated models.
It would be great if Showcase could identify what the issue is when a import fail, even the log file is not much help.