I have an issue I cannot figure out. For background, I have a gravel bike with Shimano GRX group. This situation has happened to me twice. Shifting is great and dead on and then all of a sudden I lose the ability to shift to the big ring. Its not that the shift falls slightly short or it struggles to shift, the derailleur isn't even pushing the chain. So, I readjust the FD cable and it it shifts great for several weeks. And again, I instantly lose the ability to shift to the big ring. If I increase the tension on the barrel adjusters it starts working. In both cases this occurred while I was off-road. The other thing that seems to happen when this occurs is that it feels like there is an extra click in the shifter. I am not 100% certain of that though. Initially I thought the cable slipped but the cable retainer bolt is torqued to spec. Ideas?