US-200 not working with macOS Sierra

Well, that sucks. I was guessing it was a problem related to the the end of 32 bit support, but if its Mojave too then god knows.
If anyone has a breakthrough, let us know. Although I think I will go back to High Sierra as this isnt the only piece of hardware that I cant get working with Catalina.

It worked for me. Tascam 1641 Interface in Logic Pro 10.3.2 on Mac OS Mojave (10.14.6)

Thank you very much.

Su-weeeet! This worked for my US1641 on High Sierra 10.13.6 (with latest security updates)! Logic recognized it no problem-o and I've been jamming all morning

One addendum to the process is to disable SIP before -- and re-enable SIP after -- the sudo rm -rf /System/Library/Caches/com.apple.kext.caches command. Otherwise, it throws "Operation not permitted" errors.

Summarized action steps for High Sierra 10.13.6 would then be:

• file /Library/Extensions/TASCAM_US1641.kext/Contents/MacOS/TASCAM_US1641
  
• sudo lipo -thin x86_64 -output ~/Desktop/TASCAM_US1641 /Library/Extensions/TASCAM_US1641.kext/Contents/MacOS/TASCAM_US1641
  
• sudo rm /Library/Extensions/TASCAM_US1641.kext/Contents/MacOS/TASCAM_US1641
  
• sudo cp ~/Desktop/TASCAM_US1641 /Library/Extensions/TASCAM_US1641.kext/Contents/MacOS/
  
• sudo kextload /Library/Extensions/TASCAM_US1641.kext
• Reboot into Recovery Mode (CMD+R), disable SIP from Terminal (csrutil disable), reboot normally
  
• sudo rm -rf /System/Library/Caches/com.apple.kext.caches
• Reboot into Recovery Mode, enable SIP from Terminal (csrutil enable), reboot normally
  
• sudo kextcache -prelinked-kernel /System/Library/Caches/com.apple.kext.caches/Startup/kernelcache -K /System/Library/Kernels/kernel /System/Library/Extensions

I will send you a fruit and cheese plate of the finest origins, kind Nevirtus. THANK YOU!

Thank you Nevirtus for your post.
My TASCAM US 1641 , now is working on High Sierra.

Has anyone tried this on Big Sur?