I'm not for sure if anyone has already mentioned this issue, but I have not been able to find it by way of search. We built a PC early last year to the specs of the base specified vMix reference build (I believe it was the Emerald), and have a client that is running it using vMix Pro. We spec'd a Presonus Studio 1824 USB interface to bring their audio into vMix as independent (mono) mixable channels within the vMix audio interface. Our client has noticed a steady, but intermittent, amount of audio drops while using the system, which ultimately requires them to close out of vMix and reopen a new session to correct the issue. We already checked audio bit rates to verify that everything seemed to be compatible (at least in what settings menus we could discover in Windows, vMix, and the Presonus GUI). The client did mention that they have noticed the CPU usage would rise prior to the drop, which would lead me to believe that this an issue with the buffer overloading, but when we have monitored the system ourselves we did not see this happening.

Initially we had some issues getting the Presonus to play nice when adding it as an audio input (we could add the input but it would later fail). After playing with how the independent channels were added as vMix audio inputs we were able to (seemingly) get it to stability, but now it seems the issues have reappeared. I assume this could be an issue with the ASIO driver provided by Presonus (of which there is only one version available - as far as I can tell), and we haven't had a chance to try a universal driver like ASIO4ALL so far which may make a difference.

Our biggest issue is that the system is not in-house, so we are having to make a service call to go troubleshoot the issue each time it happens (we have had over a dozen phone and web support calls and rolled a truck twice in reference to this. Of course - being intermittent - we have been unable to sufficiently reproduce the problem to find a solution when our technician is on location.

I've tried to chalk it up to operator error as much as possible, seeing as we are unable to reproduce the issue when present, but the client insist that the problem is something hardware/software related. If anyone has experience with these Presonus interfaces, good or bad, I'd like to know so that I can narrow down if what we are experiencing is an anomaly or is there a true problem that can be corrected (by replacement or otherwise).

Thanks for the advice in advance.

Thanks for the info Tom,
I'm sure the X32 would solve the interfacing issue but it is way overkill for this situation (4 wireless lav mics with limited routing in or out).
I did review the Presonus forums as well, but did not feel like the negative remarks were overwhelming enough to discredit the 1824 as an option (you can't make everyone happy).
To alleviate our issue we opted to forgo using the ASIO inputs as the audio input in vMix and instead brought the audio in using the rack unit's main outs to pass the audio to the line input on the PC's soundcard. Individual channel control in vMix was lost, but so was the concern that an asio driver conflict would occur (hopefully - see below). Oddly enough the 1824 requires the USB to be attached to the PC for the analog main outs to be operational (when we removed the usb cable the signal through the main outs disappeared). This is even when all of the digital inputs of the 1824 recognized in Window's sound control panel were disabled and only the analog line in of the soune card was active and set to default. I assume this means that main out is not a pass-through but a return mix after the inputs are processed in the Presonus application (which could still pop up as a driver problem unfortunately)?
So we now know that the rack unit is totally useless without a PC, and posssibly a drain on its system resources, in sending what should be a point to point input to output. Its a bit frustrating that this is never mentioned in the Presonus documentation. I know that the 1824 is an "economy" product but you would assume it should function as specified. I personally used a Presonus Firepod (fire wire interface) for years and it worked perfectly in any application I placed it. Maybe the frailties of the rack unit are why it was retired lasy year (in favor of a new usb-c model which is hopefylly better).
If anyone has any further info it would be appreciated.
Thanks