When you confronted did you share that you had recordings?
If not, then use what you have to finesse your investigation.
It’s clear that your location for the VAR in her home office and the bedroom wasn’t good enough to give you a clear recording. However it does tell you that she’s doing something that you question in those locations. Relocate the VAR’s; if she’s doing online sex in the bedroom its probably from the bed rather than standing in front of the dresser, it’s probably from the office-chair in front of the computer rather than on the filing-cabinet. Maybe even hide a camera since you know the where.
But friend – for every reason you think it was sex I could possibly give you an equally logical non-sexual reason. Maybe she was saying hello to a picture or the cute aerobic trainer in the online exercise recording, or talking back to Alexa or Siri. Heck… I greet a portrait of my dad that hangs in my office every morning and talk to him regularly.
"Sex" – even online and maybe especially infidelity sex – tends to have a build-up. She doesn’t just go to her home-office and contact OM out of the blue, say hello and then fingers-away! There would be some arrangement (done with some form of communications) and when the call is made some form of mutual back-and-forth build up. You only got the "hello" and no "how are you" or "he’s not home" or "I’m in the office now" or whatever.
Use those two factors: Communications (discover how, when, where and work from there) and location/positioning of monitoring devices.
If she is suspicious of you recording her then she might change locations but if there is an affair ongoing it won’t just stop. Frequency might change, but she’s going to be meeting OM in life or online somehow somewhere. People generally feel safe in their space (bedroom, office) and if she suspects you of recording her she will do a search. If she doesn’t = she doesn’t suspect you.
HOWEVER – and this is the key statement I have been making all the time: IF after a REASONABLE time you don’t have CLEAR evidence of infidelity then maybe it’s because you are searching for something that ISN’T THERE.
It's all a moot point however if you don’t want this marriage. Its extremely unlikely that infidelity factors in any way or form if you divorce. Maybe your next logical step would be to research divorce and see if there is anything you need to line up before filing.
"If, therefore, any be unhappy, let him remember that he is unhappy by reason of himself alone." Epictetus