The other thread is a good one.
I suggest you hold a strip of paper near the fuel tank cap when you open it next time and as the pressure/vacuum is released the paper will deflect in or out ..........
If it is deflecting IN (vacuum) then it may be the case that the vacuum gets so high the fuel pump can not overcome it.
This would likely be the result of a clogged charcoal canister (assuming this is a USA built bike) or perhaps the check valve in the vent line from the tank.
I carry an extra "straw" from a can of WD-40 in my tool kit so that I can close the gas tank lid on it if needed and hopefully maintain venting until I can fix the real problem (if it is a venting issue)
What is the latest news?