Channel offset does nothing

Hello,

I'm using the linuxserver/webgrabplus docker image with version V5.0.1.0.

Inside my config, I have added an offset to all my channels, as they're 2 hours behind, meaning that shows from 5am are saved as 3am.
Example:
<channel offset="2" update="f" site="live.tvspielfilm.de" site_id="ALPHA" xmltv_id="ARD alpha">ARD alpha</channel>

Unfortunately, the offset doesn't seem to work. It doesn't matter what I actually put inside the offset, it simply does not change the output. The guide.xml always contains the exact same timestamp:
<programme start="20230618033500 +0200" stop="20230618040000 +0200" channel="ARD alpha">

Did I do something wrong?

Thank you.