Why Is there sometimes only one column of a Check Box TV displaying in the manager when Columns has been set to display 3?

MODx 2.5.1 (also experienced issue in previous versions) | Browser: Safari and Chrome (multiple version ) | OS (Mac — El Capitan and prior)
Has anyone else experienced a problem with a Template Variable column setting for checkboxes in the manager not working?

I have a number of Template Variables, with input type "Check Box" and Columns set to "3". Each TV contains anywhere from 6 to 18+ check box options. To make them easier to view and check in the manager, I set the columns to 3. Sometimes I can see all 3 columns in the manager, and sometimes I can only see the first column. This problem occurred yesterday while I was working on some of the site pages.

Is this a MODx Manager issue, A Mac browser issue, or a result of solar flares?

At this moment, only 1 column or my 3 columns of check boxes is displaying in the manager. Safari web inspector states modx.jsgrps-min.js.map failed to load 404. Could this be the problem?

[ed. note: mmcgee last edited this post 7 years, 6 months ago.]