Try it and check the DVR log to see what it does (I usually open that in another browser tab while playing in the first tab).
2025/09/07 20:37:57.594118 [TVE] action=auth mvpd=Comcast_SSO requestor=ABC
2025/09/07 20:37:57.623365 [TVE] action=xvfb display=:576
2025/09/07 20:37:58.835603 [TVE] action=version product=Chrome/132.0.6834.83 jsVersion=13.2.152.27 protocol=1.3 revision=@03d59cf5ecf1d8444838ff9a1e96231304d4ff9c
2025/09/07 20:37:58.837927 [TVE] action=page_ready chromeVersion=132
2025/09/07 20:37:58.839256 [TVE] action=navigate url=https://sp.auth.adobe.com/adobe-services/authenticate/saml?noflash=true&mso_id=Comcast_SSO&requestor_id=ABC&no_iframe=true&domain_name=adobe.com®_code=&redirect_url=https%3A%2F%2Fsp.auth.adobe.com%2Fadobe-services%2FcompletePassiveAuthentication
2025/09/07 20:37:58.848122 [TVE] action=request type=Document method=GET url=https://sp.auth.adobe.com/adobe-services/authenticate/saml
2025/09/07 20:37:59.615606 [TVE] action=request type=Document method=GET url=https://oauth.xfinity.com/oauth/authorize redirected_from=https://sp.auth.adobe.com/adobe-services/authenticate/saml
2025/09/07 20:38:00.088910 [TVE] action=request type=Document method=GET url=https://login.xfinity.com/login redirected_from=https://oauth.xfinity.com/oauth/authorize
2025/09/07 20:38:00.089055 [TVE] action=auth_domain domain=login.xfinity.com
2025/09/07 20:38:02.199117 [TVE] action=wait_for_page
2025/09/07 20:38:06.153741 [TVE] action=request type=Document method=GET url=https://oauth.xfinity.com/oauth/authorize
2025/09/07 20:38:06.517365 [TVE] action=request type=Document method=GET url=https://sp.auth.adobe.com/adobe-services/oauth2 redirected_from=https://oauth.xfinity.com/oauth/authorize
2025/09/07 20:38:08.319315 [TVE] action=request type=Document method=GET url=https://sp.auth.adobe.com/adobe-services/completePassiveAuthentication redirected_from=https://sp.auth.adobe.com/adobe-services/oauth2
2025/09/07 20:38:08.319459 [TVE] action=authed
2025/09/07 20:38:08.319513 [TVE] action=wait_for_page done=true reason=auth_finished
2025/09/07 20:38:08.323702 [TVE] action=cookies num_domains=2 num_cookies=21
2025/09/07 20:38:11.175988 [TVE] stream timestamps: abc: start_at=2025-09-07T20:37:41-07:00 end_at=2025-09-07T20:37:47-07:00 live_delay=21.896984587s
2025/09/07 20:38:11.176169 [TNR] Opened connection to TVE-Comcast_SSO for ch6001 KXTV
2025/09/07 20:38:11.176224 [HLS] Starting live stream for channel 6001 from 192.168.1.8 (bitrate=8886kbps)
2025/09/07 20:38:12.254529 [HLS] Probed live stream in 1.077469637s: h264 1280x720 progressive 7024539bps
2025/09/07 20:38:12.291498 [HLS] Session ch6001-dANY-ip192.168.1.8 started in 1.115199071s
If it fails to auth, at least it doesn't remove it from the guide, so you can always try again.
I've had to try two or three times in the past on the same channel.