Report viewer not displaying same data as actually generated on pdf

I just updated some gateways (3 total) to version 8.1.37 (from 8.1.26) and now some reports don't show their correct data in the PDF viewer in Vision. The actual PDF documents have the correct data with no problem but just when viewed from vision it shows null values as squares.

Within Vision, I use a file viewer and a PDF viewer to display reports from a singular directory. All reports are generated based on tag change scripts and saved to a dynamic file structure. Users then select reports for review or printing in the file view/ pdf viewer combo. It's ugly but we have been doing this since 7.8.1. The data missing in Vision is based on an SQL joined query but nothing too interesting.

pdf viewer:

actual pdf file (in edge):

any advice or a better way to do this? I can provide additional information if required.

Hmm... you might need to work with support on this one. I have to say I'm a bit mystified.

Usually the blank boxes (often called "tofu") mean that the computer knew what character was intended but the chosen font did not know how to display that character. Is there any possibility that the installed fonts on the client or gateway machines changed around the same time as you did the Ignition upgrade?

The part that mystifies me is the report that is displaying correctly doesn't have any special characters in it. The vast majority of fonts can at least display 0-9 (and almost as many can display a-zA-Z), so something odd is going on here.