It does recognize the mec string, just make sure to setup a valid one.
Discussion
I checked. I just copied and pasted the NWC provided by coinos.io, like I did in Amethys and Primal. And the app returned this message.
Ah okay, at the current time, only Alby nwc is implemented. We will make sure to add availability for others such as Coinos.
In fact, the NWC in the web version of the client is not woking either. I tried strings from coinos, minibits and from iris client wallet. I tried the same strings in noStrudel client and it worked just fine. 