In the bedrock edition i always have an inverse crosshair (black block with white cross) when i use a texture pack.
I was already looking for the "super secret settings" as a possible cause, but also not found the one for bedrock…
who can help?
Possible fixes (try them in order):
In Minecraft, go to Video Settings, scroll down to Anti-Aliasing and turn it up.
Edit the icons.png file (to be found under textures / gui) with a program like Gimp or Paint.net and set Alpha to 1.
That would have been a question from me, thank you for finding something like that here 👍😉
Wow we don't quite know how, but we made it - thank you very much and all the best for 2021