PC with issue: Dell 7010 running Windows 10 pro with latest updates

Program: Old 32-bit program I have using for years running compatibility mode (XP SP3). The program is an old CAD program to design PCBs. Manufacturer does not support program. I have the same program running on multiple other PCs running Windows 10 64-bit including an identical Dell 7010.

Something happened recently to cause this program on this single PC to not open any file with a filename containing periods, spaces or hyphens. It opens files conforming to 8.3 as well as long filenames including file names with underscores.

Any filename with periods, spaces or hyphens causes an error saying Database "filename.dbf " does not exits.

For example:

If file name is Amp.RX.DBF, error says Database "Amp.dbf " does not exit.
If file name is Amp RX.DBF, error says Database "Amp.dbf " does not exit.
If file name is Amp-RX.DBF, error says Database "Amp.dbf " does not exit.

If filename is Amp_RX.DBF, file is opened
If filename is AmpRX.DBF, file is opened
If filename is AmpRX1234456789.DBF, file is opened

Only thing I can think I did was I tried running compatibility troubleshooter to fix another issue. I re-installed the program and problem still exists. Again program runs OK on a number of other PCs.

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Additional information.

Program and stored database files are in C:\Program Files (x86) directory. If files are moved to another directory, all effected files will open. Unfortunately program stores all configuration and scratch files in C:\Program Files (x86) directory and they cannot be moved.

Just trying to get a handle why the program won't run on this single PC.

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More info:

If I make a copy of an effected file into the same C:\Program Files (x86) folder, the new file works.

USB surge.dbf won't open

USB surge - Copy.dbf opens fine

This is really weird.