When you try to enter a ACS URL as below
https://581ebd7e-b1a3-4bc2-b33b-0d3282780e6b-xxx.xxx.xx-xxxx-2.test.com/saml2/idpresponse?relayState=client_id=qweqwebiwsbciurvbosidvhsod&identity_provider=XXX-XX-XXX&redirect_uri=https://xxxx.xxx.xxx.xx/xxx/xxx-xxxxx-callback/581ebd7e-b1a3-4bc2-b33b-0d328&response_type=code&scope=openid
WAMUI is accepting the URL upto the legnth of 256 chars as below where it is trucating the URL
https://581ebd7e-b1a3-4bc2-b33b-0d3282780e6b-xxx.xxx.xx-xxxx-2.test.com/saml2/idpresponse?relayState=client_id=qweqwebiwsbciurvbosidvhsod&identity_provider=XXX-XX-XXX&redirect_uri=https://xxxx.xxx.xxx.xx/xxx/xxx-xxxxx-callback/581ebd7e-b1a3-4bc2
Policy Server Version: 12.8.8
WAMUI version: 12.8.8
This is known defect so please open a support case to get the patch.