Lightroom Classic v15.3 on Mac OS Tahoe: importing a photo file which includes a | (pipe) symbol in dc_subject metadata causes Lightroom to hang with 100% CPU usage.

Lightroom Classiv v15.3 (on Mac OS Tahoe) has a problem importing photo files that have a pipe symbol - a | symbol - in the XMP field dc:subject.

Lightroom apparently has a problem interpreting the pipe symbol, and then hangs, seemingly indefinitely until the import is cancelled, while showing a high level of CPU usage. This hanging seems to take place at the end of the import process for this photo.

The pipe symbol is used by Lightroom to separate levels in the keyword hierarchy within the Hierarchical Subject XMP field.  Having pipe symbols also within the keywords doesn’t seem to be a problem with the Hierarchical Subject field - at least it doesn’t interfere with importing.  Also the pipe symbols in the Weighted Flat Subject field don’t seem to cause a problem with imports.

Attached is a sample file that hangs when being imported into Lightroom.  Of course, a problem file causes a batch import of photos to fail, with some number of files correctly importing until Lightroom does to process a problem file.

I have tested with various other programs that import photos with their metadata, and they do not have the same problem as Lightroom.

As a historical note, the saving of the pipe symbols in the dc:subject field was done by an earlier version of Lightroom, perhaps related to addition of keyboard hierarchies that contained empty keywords.