What could be the addon in local Arma3 folder, Launcher check (OK) for signed one but failed to find keys. Launcher displays a mes such as:
"key not found for signature. C:\program...\Arma3\@(an_addon)\addons\blabla.pbo.addon_file.bisign test failed"
addon folder is the standard one. Arma is vanilia + DLC helicopter & marksmen + addon you expect to launch. Addon is identified as a "local" one in Launcher (not on Steam). Addons are serious ones like CBA, downloaded on armaHolic. addons folder is included, keys files are present (same name as pbo files). {F26528}