I was just guessing that could be the reason. Since you still have it installed on your phone, can you try with Tron or USDT over Tron? I tested that a few moths ago when I downloaded the wallet, but I don't remember if there was an error message like on your end or if I just couldn't find those assets listed.
Same error as doge, can't add with 12 word wallet.
AtomicDEX.io might be one more alternative you can use for dogecoin, it also supports Bitcoin and other shitcoins, and you can even exchange coins if there is enough volume.
I don't like that for Bitcoin they are still using old style addresses starting with 1, and wallet is still in beta phase, but it works fine.
Probably best option for multicoin wallet is combination with some hardware wallets, but I saw other wallet called Stack also supports doge.
There are a couple of options for multicoin wallets, each have their own good and bad things. Although I don't like them in general, for a few dollars of coins they
work well enough. As I said, storing real amounts in a hot wallet is just asking for trouble. I tried atomicDEX.io it did work with no issues, didn't do something I needed, don't remember what. But no problems with it not working.
Other than being closed source, I don't know last time Coinomi developers updated their desktop wallet, not sure if similar situation is with their mobile app.
March of 2022.
-Dave