Odd.
I made one test and didn’t get that result. I opened a different file, added dimensions to it, saved to TC and opened the viewport link. I did get the black text boxes.
I copied the model with the dimensions into a new file, saved it to TC and then opened the link to the viewer and it works as expected.
Perhaps you could try that? There shouldn’t be any difference between my two files except the file name so it’s kind of a puzzle and, if it fixes it for you, not a very satisfying fix.