Mathcad Prime 12 freezes after changing result units

I am using PTC Mathcad Prime 12.0.0.0 (Academic). Whenever I change a result’s displayed unit, the calculation region turns grey and dependent expressions stop evaluating. Automatic calculation is enabled, but the AUTO indicator remains orange.

Simple example:

1. Define d := 3 mm

2. Define a := d³ · π and evaluate it.

3. Change the result unit from L to mm³.

4. The result displays approximately 84.823 mm³, but the region stays grey and a subsequent evaluation of a shows “?”.

Recalculating the worksheet does not resolve the issue.