The objects being dimensioned here are not blocks, but the erratic sudden displacement behaviour is reminiscent of the block dimensioning bug.
Having trouble with an Angular Dimension in layout space snapped to objects in model space which, when correct, looks like this. :
I’ve recreated it from scratch many times, replacing a corrupted version which keeps appearing without any trigger that I’m aware of. The dimension always looks like the above after I’ve just created it.
Though the corrupt version is identified as an Angular Dimension (in Properties), it doesn’t look like one; it looks like this (the text of the dimension in the image below - as displayed on my machinery - is cropped out on this forum web page unless the image is opened):