Hi, newbie here... I'm having trouble with the exports to be played back in ANY format. What am I doing wrong? Everything worked perfectly on my old 8.5 but it burned in a house fire.... (no, not my fault) ... what should I be looking for?

you need to select all tracks before export (hold CNTRL+A).
and make sure you have selected your in/out points in the timeline, or by using Edit\Select\from here and then Edit\Select\thru here.
 
 
if this doesn't work, then look at your export settings on the export windows. you might be missing some check marks / wrong selection.

Problem Solved --- turns out I downloaded a fresh set of codecs and rebooted.... everything fell into place.

iirc x2 has a version of up to x2b.. many fixes from x2a