Select rectangle tool. Mouse click on a location. Move the mouse to create rectangle outline.
Dimension box shows dimensions in feet and inches.
Attempt to type 12".
As soon as the shift key is pressed before " a dotted diagonal line is drawn in the rectangle and the dimension box changes to a new dimension with minus signs in front of each coordinates.
Attempt to type 12ft.
As soon as the f key is pressed the offset tool is selected and the dimension box changed to “Distance” and is blanked.
Attempt to enter 12’, 3".
Same behavior as soon as shift is pressed.
Attempt to enter 12’, 3in.
Same behavior as soon as i is pressed.
Same behavior with circle tool.
In system preferences there are no keyboard shortcuts.
Use smart quotes and dashes IS NOT checked.
Text boxes and lists only IS checked.
Reproducible on an (old) MacPro running El Capitan and a (new) iMac 27 running High Sierra.
Suggestions on what is hijacking the shift key or a letter key on these Macs?