Sophos XG & Exchange 2019 - WAF not working - URL hardening

Hi,

I'am lokking for some help to come over a problem with Exchange 2019 and WAF with static URL hardening.

I use this poular documentation here: https://www.frankysweb.de/sophos-xg-18-webserver-protection-und-exchange-2019/
and it did not work as expected. I get the 403 error "no signature found" because there is no match to the configured entry URLs, but this must be wrong I think?

There are several other discoussions out here, but no real solution:
https://community.sophos.com/utm-firewall/f/web-server-security/95012/can-t-publish-owa-web-page---no-signature-found-error
https://community.sophos.com/utm-firewall/f/german-forum/93822/request-blocked-the-web-application-firewall-has-blocked-access-to-owa_blwdawpfyy_form-for-the-following-reason-no-signature-found
https://community.sophos.com/utm-firewall/f/web-server-security/50294/exchange-2013-not-working-through-waf
https://community.sophos.com/utm-firewall/f/web-server-security/102809/hardening-signing---no-signature-found

.....

The only way to get it work is to set an exception in the firewall rule with "/owa*" for example.

Is there any documentation for a end-to-end configuration. We have nothing special there.