Navionics map only showing part of the lake

Everything I have is old so keep that in mind. Lowrance HDS 7, Navionics chip MSD/HM-S. It has worked fine until recently when it is not showing any data North of Wolf Island on Lake Ray Roberts. I put it in another Lowrance unit and the same thing happened on it so I don't think it is the unit. Has this happened to anyone else and is there a remedy I haven't tried yet? I called the Navionics help line and the lady wasn't sure about that and the advice was to buy a new chip. I looked at other area lakes and it seems to be doing fine on those. Any suggestions would be helpful.

I have never seen that happen, let me shoot an email to Navionics technical guys and see what they say....curious about this one as well.

I have the S2 version (2006) 512 MB, and it shows all of Ray Roberts.

First contour is 12' and then 10'contours after that. 22',32', 42',etc.

S is 2005 and may have less coverage. That card is 256 MB.

I just responded to your PM, sorry for the delay, I was at the Sealy event Thursday thru Sunday of last week.