Auto Blog - Fails to process, stuck in January 1970

Auto Blog stopped working with the plugin update to v4.0.3.

It worked well before said update. With no plugin settings changed, it fails after said update.

Problem
Feeds are no longer processed. This applies to both existing (worked in previous version) and newly created feeds.

Feed dates ("Last processed" & "Next check") show "January 1970" but hovering the mouse over that text still shows the correct "Next check" date as a tooltip.
Newly created feeds aren't processed and thus show "Never" as "Last processed".

It doesn't matter what settings are applied: import post, n posts, start after and/or end before date...
Standard removal and installation of the plugin doesn't help.

Setup
Plugin individually activated on the main blog of a MU setup. WP runs the latest release (3.8.1 at this writing).