Unfortunately, that's AI. Very very poor IT systems... and they're still struggling with scheduling and plane deployment post their merger.
Forget one month out.. I have tickets that are 9-10 months out and they're constantly tweaking those schedules as well... constantly messaging and emailing about 5 minute schedule changes!
Others have reported that they can now credit all (including ex-UK) flights to UA, maybe that's one less issue to worry about.