Sahil, thank you for your reply and sorry for the delay. Unfortunately, your suggestion did not solve the problem. I recently updated PS (CC2017) and ACR to their latest versions, and after that reinstalled ACR as you suggested.
I was just working on a previously edited NEF file. I stored the original edits by making a snapshot called v3, then applied new edits using the brush tool, saved it with snapshot v4, opened it in Photoshop and saved it as a TIFF and printed it.
I wasn't fully satisfied with the print, so went back to the NEF and it opened correctly with v4 settings. I adapted a few edits, saved the result in snapshot v5, and opened it in Photoshop and saved it as a TIFF again.
Again I decided that it wasn't perfect yet and reopened the NEF in ACR. This time it opened with global edits only, but without any local (brush) edit. However, if I click on snapshots V4 and V3, all edits, both global and local, are shown correctly.
Closing and reopening the NEF nor quitting and restarting Photoshop make a difference. I opened the XMP file with a text editor and can see that the data for v5 is in the file, but I'm not an XMP expert and cannot tell if there are any errors in it. The XMP's file size is 2.3MB.