Outlook definitely engage in aggressive blocking of netranges, but I’m pretty sure they don’t use UCEPROTECT to do this since I’ve seen servers caught in Outlook netrange blocks despite all the public RBLs (including UCEPROTECTL3) showing no problem.
Just to be sure, you are using the Outlook form[0] and not the Office365 form? Have you signed up for SNDS?[1] All these hoops are pretty dumb, and I don’t think they have updated any of these systems since the mid-2000s so they are also pretty terrible to use, but here we are.
My limited personal experience with Outlook’s removal process is that it’s just slow and confusing (sometimes 12 hours for a response, sometimes the response emails are empty). The last time I had to do this, their TLS certificates had expired (and they use HSTS), so I could not even get into SNDS for half the day until someone there finally noticed and deployed new certificates.
[0] https://support.microsoft.com/supportrequestform/8ad563e3-28...
[1] https://sendersupport.olc.protection.outlook.com/snds/