I use navionics, but without the card but mine is linked to my other unit, which I haven't had a problem with so far.and I wouldn't think it'd be doing that because of the card, they're made to be compatible. But at this moment I'm not totally sure on what my issue is.
Here in about a week I'll probably take it in to fun-n-sun, and I'll figure it out through them. I'll post what it is on this thread. But id prefer to know/do it myself.