EveryCircuit uses Google's "Native Client" (NaCl) which is a sandbox system that allows webapps that use native code, a while ago an update disabled its use by apps that aren't installed through the chrome store. Everyone is supposed to move to WebAssembly, but every circuit hasn't.
There is a way to reenable it - to go chrome://flags/#enable-nacl and hit 'Enabled'. Apparently google laid off its entire Native Client dev team, so who knows if the sandbox is still secure and there seems to be no way to enable it on a site-by-site basis.