[Plugin: Events Manager] Update to 5.2.1 kills custom widget

I was using a custom shortcode in the sidebar widget. After the update to Version 5.2 it outputs complete nonsense.

This is the shortcode, which worked until then
[events_list_grouped limit="5" pagination="0" format_header="<ul class='eventwidget'>" format_footer="</ul>" ]<li> #_24HSTARTTIME Uhr | {is_long}bis #@_{d. F}{/is_long} #_EVENTLINK <br /><small>#_ATT{Predigt}</small></li>[/events_list_grouped]

Now it starts spitting out code like this:

#_2400stCESTAMRCESTUTC1AugE 134550720012Tue, 21 Aug 2012 00:00:00 +0000 | {0000_Dienstag2012812}b0000 #@_{21. August}{/0000_Dienstag2012812} #_EVE2CEST112K <0008amDienstagTuesday>#_AMCESTUTC{+02:00Tue, 21 Aug 2012 00:00:00 +0000Europe/Berlin21001231}

What could be wrong?

http://wordpress.org/extend/plugins/events-manager/