look like i found where i have errors:
in .rvmat i have texture="#(rgba,8,8,3)color(0,0,0,1)"; after changing to texture="#(argb,8,8,3)color(0,0,0,1)"; problems with packing WRP disappeared.
But here we have eximple with rgba. And i cannot understand why error appears only with packing WRP.
OLD Material
NEW Material

In T186423#2705473, @Geez wrote:

Hello Kiker.
We will require the files you use to build it and as well as the settings of addon builder you use.