"Why won't Word print the right mathematical symbols?"
A couple of years back while proofing a submission to the FDA - They like things accurate. - I spotted a simple equation that was in error. It was something like "X is greater than or equal to Y" but the symbol shown was 'equals'. (Like "6 ??? 5" printed as "6 = 5". The error stood out, thankfully. "Less than or equal to" presented the same wrong information on paper.
A bit of sleuthing showed that the Konica BizHub font codes in firmware made the mistake. I corrected all users' machines to NOT use printer fonts, but Windows fonts instead and the error stopped.
But it was printing to PDF that got me on the right thinking path. Testing on HP printers didn't replicate the error; Konicas always messed it up. Fixed!