As far as I know this is a problem exclusive to the Gen 2. No fix.
HDS 10 Gen 2 on boat shows flats names perfectly with Lakemaster chip. With recent updates. I think Fife’s uncle had this same problem a few weeks back on his HDS 10 as well……Fife?
Just to throw my 2 cents in here, I read that someone commented that Navionics is not that great on Millelacs, they have done a bunch of cartography updates and it is an excellent choice for Millelacs. Just a reminder to check out the Navionics website to see if your chip qualifies for the Freshest Data program. Another cool feature they are coming out with is UGC user generated content, you can record it send it to Navionics and they will then update the cartography and you will be able to update your chip with this new data.