Presonus Studio 192 w/Pro Tools 2018.4 - sample rate getting stuck?

[skizzo]

I am just finishing off what felt like a major upgrade going from Max OSX 10.6.8 to 10.13.4 and Pro Tools 8.0.5LE to 2018.3 (and now upgraded to 2018.4)

I was getting quite frustrated at first because I couldn't wrap my head around the issue due to it seemed so random at first. The Presonus Studio 192 can select a sample rate up to 192khz but it seemed like it was stuck in certain set points. This became very obvious when say selecting 44.1 but it would after a few seconds jump back to 48 (where it was "stuck"). This was visually noticeable using their include control software "Universal Control". Now even if I got it to switch to say 96 I would always get the same error when opening existing sessions, whether they were true 2018 sessions of 8LE sessions, or even creating a new 2018 session. This error would say basically Pro Tools cannot either open or create the session because it couldn't set the sample rate. However going back to the "Stuck" rate of 48k I could then open up any 48k session, or 44.1k session. It makes sense that it auto selects the sample rate as long as it falls within the same input and output channel count. Seems like the issues arise as I change sample rates that will impact channel count.

As some background I am only familiar with Pro Tools 7 and 8 and really. Using either HD systems or Digi interfaces like the 003 rack+. So I was used to being able to load a 44.k1 session and then immediately opening a 96k session no problem. The latest version doesn't seem to want to work like that due to what I believe is because I am using a third party interface?

It acts stuck even if I powered off the interface, even unplugging the USB cable, restarting or shutting down computer. The sample rate the unit powers on with, if its not the "stuck" rate it still wouldn't work. I saw some notes from Presonus about some older OSX version not playing well with USB 3.0 ports or cables and I tried all combos there but did not notice any difference. That includes using the 3.0 cable into a 2.0 port. a 2.0 cable into the 3.0 port. and a 2.0 cable into a 2.0 port. All acted the same, but at first I thought I saw an improvement with 2.0 cable and port but that was quickly proven wrong.

So here is what I FINALLY discovered as a work around. I should ALWAYS create a new session at the desired sample rate prior to loading a previously saved session. Seems like Pro Tools will for example have 48k selected in the create new session window, but I may have the interface selected at 96k. So it makes since it couldn't create a new 48k session. However if I change the create new session sample rate parameter to 96 it will create that session no problem (as it should) and THEN at that point can I now load up any previously saved 96K session. If I tried to load the 96K session up before creating the new one it would give me the sample rate error.

I believe the error is something like "pro tools could not set your audio device to the correct sample rate" (I am not at my computer right now so sorry for not having exact error text

So I am wondering is this a normal "quirk" of working with third party interfaces with Pro Tools now-a-days? If not are there some settings that I am not aware of that are preventing Pro Tools from setting the same rate to match that of my Presonus Studio 192? I am overall pretty happy with the system but am a perfectionist and would love to find a better solution that doesn't involved creating new sessions just to delete them in order to switch from different channel counts (ie 26 IN w/44.1/48khz to 10 IN w/176.4/192khz) I am not even sure if this is an issue with the interface, the interface drivers, Pro Tools 2018.4 or due to being on OSX 10.13.4. I have reinstalled the interfaces drivers and Universal Control as well as the firmware.

One last thing to add is I don't always get the Pro Tools message saying it must quit/restart due to channel count changing. And this an obvious thing for me because it should want to quit/restart if going from 48khz to 192khz or any sample rate that would impact my interfaces I/O count. If I am unsure of where the rate is "stuck" I have to change the sample rate back and forth until I get that message, which indicates I finally got Pro Tools to recognize what the interface was set at.

My setup is as follows
Mac Pro 4,1 (flashed to 5,1)
2.6ghz processor - 4 cores
48GB Ram
OSX Version 10.13.4
Pro Tools Version 2018.4
Interface Presonus Studio 192