Hi @thomas,
Unusual indeed! Because of the way the video is cropped, I can't quite tell what commands you're using. It looks like you might be clicking the dimension button (DIM command). Are you using a different command/button to create the dimensions with the infinite lines? Does the DIMLINEAR command yield the same results?
Not sure if it's related, but I'm curious if turning hardware acceleration back on affects anything. Your graphics card meets the minimum requirements for AutoCAD LT 2019. If anything, you might try turning off line smoothing (LINESMOOTHING command > off).
Does this happen only with dimensions using this dimstyle, or do any and all dimensions have the same issue?
If you haven't already, try resetting AutoCAD to defaults. This will rule out any custom settings as potential causes.
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Chris Preece
Technical Support Specialist