We have a fairly robust internal report which I've been using to kick out standardized metrics each month - huge time saver. This report is currently 35 visible pages when published to the online service. One interesting problem I'm running into, is that if I click the "next page" arrow at the bottom of the page a number of times such that I reach the end of the report, I am unable to click back and view previous tabs not shown in the current "view". This varies by user, but in my report, clicking to the end of the report leaves me with 11 accessible tabs, and no way to page back to the beginning of the report. It's like the JS breaks almost.
I've not had any luck in finding detail on a maximum number of visible pages in a report, and am confident that my data model, while nuanced, is not particularly large relative to what others are using.
Based on my test, I cannot reproduce your issue here. I used the latest version of desktop : 2.61.5192.321 64-bit (August 2018). And I tested in Edge and Chrome. Could you please tell me which kind of your Browser? Please check the supported Browsers for Power BI here.
Is your issue solved now?