Had the same issue and similar error for one blueprint (based on the class for which I changed the last). Deleting Binaries and re-packaging solved the issue. I suspect the issue happened, because I packaged the project after “Live Coding” (Recompile and reload C++ code for game systems on the fly" from the editor). Normally, after changes in C++ I would close the project, recompile it properly, start the editor again, and only then package. That time I was lazy and didn’t do that restarting and proper compilation step, and hence - probably - the error.