Ouch, this doesn't look good and there are various reasons why this could happen. The best ways to solve this:
Update Photoshop to the most recent version to avoid any legacy bug
Try to import a single layer before selecting many at once
If you get a warning of unsupported types of layers, convert them into plain image/vector layers
And check that your layers are not inadvertently linked as clipping masks (a down-facing angled arrow should show up on the left of the layer's preview. In this case, just press
Alt + clickbetween two layers to break this link):
If none of these tricks work, then just send us your PSD along with a description of which layers do not import to hello@fontself.com