Method 'GET' not supported using SAML app

❌Unsolved🪵Login☁️Zitadel Cloud🧩Integrations❓Question

Hi. I have a SAML application configured in Zitadel. When I attempt to login to the app using SSO, I am correctly redirected to Zitadel for entering my credentials. However, I am not successfully redirected back to the app. Instead I get "Method Not Allowed", "Method 'GET' is not supported." If I am already logged into Zitadel when I attempt to login to the app using SSO, the app successfully loads. I have tried configuring a second SAML application in Zitadel and I am getting the same behavior. I must note that these are commercial apps (i.e. not created by me). Any idea as to what is causing the Method not allowed and why does it work if already logged into Zitadel?