Not enough free space to update to Mac OS 12.6

Today I attempted to update to Mac OS 12.6 and got the following message:

I deleted a large number of files through Manage Storage then restarted twice. Here is the result after this process:

It still would not let me update even though I have 386.25 GB free. It appears that the purgeable space of 368.95 must be subtracted from the free space which leaves 17.3 GB, which is less than the 18.76 needed to update.

What to I do to remove this purgeable space? Deleting large files is not helping since the ration of free and purgeable does not seem to change?