Ok Mark, from a distance it is hard to diagnose. What I say next may miss the real cause because I can only comment on generalities.
I do not like to see reference to sound card in these types of problems. Forget sound card, those settings are for other things. I think there needs to be a tutorial on the valid uses of sound card and line out. For now disable them - uncheck their enable buttons.
In ESDR2, VAC should be like this except that your RX gain and TX gain maybe zero or at other levels. Right now set them both to zero.
Windows sound system has some bearing on VAC. The audio path does not use this route provding that in the VAC Control Panel you have not checked 'Volume Control' for either of the VAC lines used by MMTTY. The Golden Rules for Windows sound system:
Microphone access must be on (Windows considers every digital application to be a microphone). In Windows Settings, Microphone page, ensure it is on and then scroll down to 'Allow Desktop Apps to Access Microphone' and ensure that is on.
In Windows Settings, go to the Sound page. Ouput Device should be your Windows Speakers, whatever you listen to computer audio with. Input device should be your Windows microphone. If you do not have one, set this to a dummy entry, anything other than a VAC Line. Nothing on this screen must point to VAC. With your digital apps of your choice open, scroll down to App Volume Device Preferences and for MMTTY set as below:
Incidentally, this work is largely 'set and forget', no need to revisit unless you later install a new program with audio that might set this stuff to default.
Back on the previous Sound page, on right hand side click Sound Control Panel. Now nothing here needs their properties setting but the two Windows devices we just set up, Speaker for Windows audio and Windows Microphone (or whatever was picked as a dummy) must be set to Default Device and Default Communication Device. There will be Speakers on the Playback tab and microphone on the Recording tab. This is so that any computer audio, real or noise generated by computer activity, stays in the Windows audio system and is not allowed to affect digital or worse, get broadcast.
Close all programs and reboot. Relaunch ESDR2 and then MMTTY and tell me the status of MMTTY TX and RX.
Regarding VAC - there is a new version 4.64 that you can get by amending your download link sent to you when you registered. But this is not important right now. If you do later install it, you will need to set again the Default Device and Default Communication Device in the Windows Sound Control Panel.
Just for completeness, irrelevant to your MMTTY issue because you have the Muzychenko VAC, there are the VAC Line properties. These do not matter unless you use a different virtual audio cable software, like VB Cable/Voicemeeter Banana, or you have Volume Control enabled in the VAC Control Panel (you should not do that except if there is too much audio gain for WSJTx/JTDX and you need to reduce it more than can be done in ESDR2 (a very rare senario)). Then the following settings apply: