The plugin is experimental and overrides core tiddlers, so this is to be expected until the plugin is updated. This is not an issue with the core.
I may have spoken too soon, that looks like it could be a parsing issue. Will need to investigate.
This doesn’t seem to parse accurately on the pre-release:
\widget $dropzone(importTitle, autoOpenOnImport, contentTypesFilter, class, enable, filesOnly, actions)
<$genesis
$remappable="no"
$type="$dropzone"
importTitle=<<importTitle>>
autoOpenOnImport="no"
contentTypesFilter=<<contentTypesFilter>>
class=<<class> enable=<<enable>>
filesOnly=<<filesOnly>>
actions="<$action-log/>"
>
<$slot $name="ts-raw"/>
</$genesis>
\end
<$dropzone/>
There is a missing closing bracket > in the override of the edit template for the attribute class for the genesis widget in the plugin. The parser has seen some changes and seems less forgiving of such errors than in the past.