Because common publicly available URL shorteners (such as bit.ly and tinyurl.com) are frequently used to launch spam campaigns, mobile operators have begun to stringently filter and block all messages using such shorteners. Unfortunately, no notification of this non-delivery is communicated to the sender (or intended recipient).
Your web server team should be able to come up with a means of shortening the URL on your server by using a shorter name for the file, such as d.html, or creating a directory with a short name and renaming the file as index.html and placing it in that directory, https://example.com/d/ or something similar.