export of multiple images from LR to PS to open in layers gets stuck in mid-import

In the last few months, every time I try to export multiple images from LR to PS using the "open as layers in PS" function in LR, it gets stuck after only 3-4 images open as layers in PS. Typically I get 2-3 layers in one window of PS, then a second window opens for a third or fourth image which is labeled by PS as background. But I am usually exporting around 15 images for focus stacking, and it stops the import in PS after only the first few images come over.  I am fully updated on both LR Classic and PS 2020. Help!