Shimano GRX RD-RX400 RD w/ 11-42 cassette

Has anyone tried the Shimano GRX RD-RX400 rear derailleur with an 11-42 cassette? I am currently running a 1x11 using Ultegra 6800 shifters and rear derailleur with a WolfTooth Road Link and an 11 speed 11-42 MTB cassette (w/ 42T front chainring). It has trouble dropping into the 11 tooth ring sometimes while riding, so I am looking for a setup that doesn't rely on the Road link. I know the GRX RD-RX400 is only rated to 36T max, and the GRX RD-RX812 is for 42; but shimano is very conservative with capacity, so I am guessing it would work, and be a less expensive option. I also know that the RD-RX400 is sold as a 2x10, but it uses the same cable pull as 11 speed (like the older Tiagra group before it).