CF7 throws IE compatibility Mode

Hi,
after installing a clean wp IE11 shows normal appereance.
Then I installed the CF7 plugin and it brings WP in Compatibility Mode (IE8). Even after uninstalling and deleting the files (normal way) it doesn’t bring the IE back to normal Mode..

Any ideas how to handle this?

Thanks Torsten

https://wordpress.org/plugins/contact-form-7/