I'm at NAMM today so only got a few min.
In Windows there are aways a set of WDM and sometimes WASPI drivers for an audio device. Professional audio devices also include ASIO drivers so an audio device may have 2-sets of drivers.
The IFFW has both of these drivers sets. Right click the speaker icon in the lower right and select Playback, you should see the iFFW listed and may have a green check mark to indicate it is the Default Windows audio device. Click on it's icon to select and then click the Properties, button lower right, then click the Advanced Tab, then click the drop down to select the desired sample rate.
If you don't use or desire Windows sounds via the IFFW, then you can disable the IFFW from Playback Tab where you click Properties, click to select the IFFW, then right click Disable. Do the same for the Recording Tab.
This may or may not be the issue and fix.
Check in Device Manager under Audio and see if the Tascam or IFFW is listed. If it is not listed then Windows doesn't see or recononize the driver and it won't work until it does. You might try also try using a different Windows FW driver for trouble-shooting.