Glad to see I am not crazy. My only solution ATM is to use the System Default setting for sound output in Tidal options. This seems to have the same SQ (though in switching from one to the other, the Eitr output setting sometimes appears to sound a tiny bit better, but this may be my imagination or a volume matching problem) and I never get the distortion problem in Masters (over the last few days at least). Although the app still refuses to advance a track on occasion, it is rare with this setting (well under 5% of the time opposed to at least 15-20% with the output set to Eitr).
FWIW, I am pretty sure (but could be wrong) that the separate Tidal quality settings for HiFi and Masters was instituted before i got the Eitr in mid-August. The worst problems with the output set to Eitr have always been with Master recording, though the exact problem has changed. Initially, tracks played fine and would advance on Master recordings, but on advancing, it would skip a track, i.e., it would play track one of an album and then automatically play track 3, then track 5, etc. (It was at this point that I contacted Tidal support, who were so unhelpful and snippy that I am itching for a viable alternative). However, that problem went away after a few weeks, never to recur. Instead, the tracks advanced correctly, but most of the time playback would be distorted until manually restarted.
UPDATE: This seems almost certainly to be an Eitr problem, or at least a problem in how the Eitr interacts with the Tidal app.. I played two Master albums that gave me problems with the Eitr; one on the Fulla 2, one with the wireless Logitech G933 gaming headset. (The G933 is a recent purchase that I am almost certain to return. It works with a USB dongle transmitter and I got it to see if its virtual 7.1 sound was effective with games. It really isn't and its SQ, though probably more than adequate for gamers who have never heard a decent headphone, is a joke compared to every other can and IEM I have.) With the Tidal sound output set to the respective USB device, every Master track played perfectly without any distortion. The tracks all advanced automatically with the G933, though 25% of the tracks (two of eight) would not advance with the Fulla 2 but buffered until manually advanced. This is a very small sample, but given that almost every Master track will distort until restarted manually with output set to the Eitr it is very suggestive.