Loss of bottom plot and depth

[JPLarry]

I have a Dragonfly 5 Pro that I've mounted to my Jackson Kayak Cuda 14. I did a through-hull mount with the transducer being in the center of the kayak. I made a foam block to mount the transducer in (there is no foam below, this was just to keep the transducer properly aligned). I then filled the space with the transducer with Marine Goop and stuck the transducer in. The worked great for probably about 3 months, when the bottom plot and depth stopped working (this happened in late October and I didn't think much of it at the time because I was fishing in very shallow water when the depth wasn't reliable anyway). But in taking it out now that it's warm again, the bottom plot and depth still do not work (GPS, speed, bearing, water temperature all do).

I looked at the pinned posts for solutions and did update the firmware, but still no change. Given that I am in a kayak, I can comfortably rule out speed or air pockets as a potential problem. I take the unit inside after each outing, so it's not subjected to the elements constantly.

Any help would be greatly appreciated as I really could use a depth and bottom plot as it warms up! I'm attaching what the bottom plot looks like as well as how the transducer is mounted.