Sprite textures get destroyed during run time?

[unikronsoftware]

This sounds like a Unity bug to me As prime31 said, he just provides a texture, unity doesn't seem to be behaving here. I'd suggest reporting the bug to unity, but without a reliable repro case, theres close to no chance this will be looked at...

[grit]

Well, maybe I will find some time to write a more clear report to unity describing this as a simple-to-reproduce-step-by-step-example.
In the meantime I use my workaround.
Nevertheless thank you very much for your kind support.