The attached Dorico 4 file started as an import of a music xml file which was exported from Sibelius Ultimate in October 2020 (probably version 2020.9).
In Dorico 4, I changed the time signature to 2/4 in bar 29, then changed it back to 4/4 in bar 30.
The problem is that bar 31 has only two beats, though it’s in 4/4.
Time signature signposts are visible, so there aren’t any hidden time signatures.
In another version of this file, I removed all of voice 2 and then created a 4/4 time signature in bar 31. The time signature appeared, but the measure still only contained two beats. (The attached file does not include this modification).
macOS Big Sur 11.6.4
2022-02-24 XML Import - 2-4 bar.dorico (770.2 KB)