Bug: Special character "?" break text in posts (feed to post)

Thanks for the great plugin! Works fine – only one small issue, maybe utf8 is not supported. I′m using the plugin to create posts from rss. Sometimes the character “?” breaks the content – the “?” and all characters after this are being cut off.

Example:
(Original from RSS)
Drei Hunde bei?en ihre Frauchen Augsburger Allgemeine Gegen Mitternacht ging eine 73-J?hrige noch kurz mit ihrem Hund.

(Post)
Drei Hunde bei

Some posts where a “?” is in the text are fine others fail. I′m using only one feed to create the posts.

Plugin Version 2.67.2

https://www.ads-software.com/plugins/wp-rss-multi-importer/