Hey Nate,
This looks like Data in fields with Regex formats changes appearance in 7.12+ · Issue #8129 · specify/specify7 · GitHub, which will be fixed in v7.12.0.7 by PR #8152.
The error message
"value '[0-9\\\\\\\\-]{3}.:####' doesn't match formatter /^[0-9\\\\-]{3}.$/:####\"
indicates that there are ^ and $ characters in the format that aren’t in the field’s value.
When I add the same format to a local database on v7.12.0.6, the XML editor reveals that those characters are included in the format although not shown in the visual editor.
To work around this, you can correct the format definition with the XML editor. The format will be enforced as expected so long as you can avoid the visual editor. See Field Formatting and Auto-Numbering: Example #3 and Regular Expression Formatter Setup: Example Implementation 2 for guidance on what the value and pattern attributes expect.
If you’re interested, there is a branch of v7.12.0.6 with just the fix in PR #8152 added that we can direct you to.