Can you attach you preferences file? Maybe this is related to bug #371386 “Circle or ellipse is invisible” which was caused by very small numbers for start and end of the arc. If I change one of the start or end values to similarly low values as mentioned in bug #438141 (duplicate of bug #371386) I can reproduce your issue or an odd behaviour of the arc tool similar to your description.
Can you attach you preferences file? Maybe this is related to bug #371386 “Circle or ellipse is invisible” which was caused by very small numbers for start and end of the arc. If I change one of the start or end values to similarly low values as mentioned in bug #438141 (duplicate of bug #371386) I can reproduce your issue or an odd behaviour of the arc tool similar to your description.