Maiden voyage - long - could be boring to some

[lamb]

that's funny. Welcome to kayak fishing. sounds like you spend some time on the water too!
I had the same thing. I very much got into kayak fishing as it seemed so simple, pop your kayak in the water and go. NOT! First times out there I was without something. Then you find a place for everything, keep 'em in the crate (that's what I do), deploy otw, pack in when back.

For the sliding straps, you may be strapping the wrong way. You have to pull it through so the lock bar with teeth can bite into it. You can put it the wrong way so it kind of slides through, never bites.

Other than that, maybe malfunctioning straps? It's unlikely, if they're new. I have had them get all worn out and shinny, so the teeth slide on that one spot. I stopped using them, keep 'em on a side for Baja strapping, more kayaks. Maybe check that too.