Does this happen in every (RD -> Big Ring) gear? I was wondering whether this is the FD auto trimming depending no the gear you’re in. Either way, even in the middle range of the cassette you should be able to get the FD to its outer most range by pressing the big-button-on-left-shifter twice.
Also, you may have already seen this page, but I thought I’d mention it anyway: https://bettershifting.com/set-up-front-derailleur-limit-screw-adjustment-bolt-one-bolt-derailleurs/
(this information is also in the dealer manual, but personally I find it’s easy to miss a step or two in the dealer manuals).
The next bit is not part of my reply to your issue, but just something on the support bolt.
A Di2 bike can work without, just like TheOtherOne says. (according to Shimano the support bolt not only helps the FD stay in place though, it also protects the frame and it should always be used on carbon frames.)
When I set up my 6870 bike I forgot about the support bolt and have never ‘fixed’ that on that bike. I did experience some dropped chains when shifting to the big ring at first though.