Project opens in v15.x but not 22.x

I just reinstalled Windows 10 on my workstation, and upon installing CC and PPro to the most recent version (22.5 - I had previously been using some version of PPro 2021 - i think v15.x), I found that Premiere opened certain older project files originally created in version 15.x (with the usual re-naming because it was a newer version), but it would not load one particularly large project file. Other than being 'larger' (linking to several TB worth of source footage on my local QNAP) that project file shares all the same characteristics of other project files which load into 22.5 perfectly. What could be causing one particular project file not to load in version 22.5? I've installed the last version of 15.x (v15.4.5) and it opens the file perfectly (as well as all the others).

Thanks.