[TS-328] AV not working since installing 4.5.4.1741

[Grommish]

Since the last Firmware Update, ClamAV has not run and is failing to update. Since it's a core app, I can't find it in the App Center, and the .cvd files are returning Invalid File Format. Did ClamAV change and QNAP just hasn't caught up, or is something else happening?