I just figured out what had happened. I updated to LR CC Classic from LR 6 with permanent license. So there are LR CC Classic and LR6 on my PC at the same time. For some reason the LR CC Classic shows that I have permanent license too. When updated to V7.3, LR CC Classic requires to convert presets to XMP file. I think this is where the problem occurs. When you have both LR6 and LR CC Classic installed on your pc, the conversion won't happen which lead to the problem you referred above. Finally I resolved this problem by removing LR6 and reinstall LR CC Classic, then the files started to convert and everything worked fine. After that the permanent license for LR 6 will be invalid, and you have to purchase plan for LR CC Classic. It seems that Adobe was not intended to let you use LR6 license for LR CC Classic however for some reason the LR CC Classic would be mistakenly licensed when coexisting with a licensed LR6.
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