The AVX2 plugins folder should contain AMACinedeckMov and inside that folder there should be a dll for MPEG2 called mc_enc_mp2v.dll Path on PC: C:\Program Files\Avid\AVX2_Plug-ins\AMA\AMACinedeckMOV
If that file has been quarantined by Windows Defender or other AV software, it would explain the encoder missing error.