When the user clicks on a date field button to pop up the calendar, the user sees the calendar in the top left corner of the form:
Confirmed in Madrid, but can also happen in Kingston and London
In the console will find the following error:
incident.do:2644 RangeError: Invalid language tag: en.us
at Date.toLocaleDateString (<anonymous>)
at e._showMonth (GwtDateTimePicker.js:288)
at e._createControls (GwtDateTimePicker.js:93)
at e.initialize (GwtDateTimePicker.js:37)
at new e (js_includes_doctype.jsx:3)
at Array.<anonymous> (incident.do:2642)
at x (js_includes_ui16_form.jsx:11103)
at wait (js_includes_ui16_form.jsx:11103)
at Object.runQueue (js_includes_ui16_form.jsx:11103)
at Object.getScripts (js_includes_doctype.jsx:243)
The code is expecting "en" instead of "en.us"
In the filter navigator go to sys_properties.list. Search for glide.sys.language. Check the value that is set. If the value is "en.US", change it back to "en" which should resolve the issue.