The problem is common to all variants but it appears that there are known batches of fuel pipes that are OK if the wording in this article is accurate. As the Italians have checked all 10 of their aircraft already we can assume that it is doesn't take long to do the checks and hence why the F-35B / HMS QNLZ trial schedule has not been affected.
U.S. Military, Foreign Operators Ground Their F-35s To Look For Faulty Fuel Tubes - The Drive