You guys with your Pan F LIK properties are funny. Try developing your film sooner. It should be noted Kodak, Ilford, Agfa etc. always recommended processing any film as promptly as possible after exposing, for best results.
Never had this issue on any of their other films. There is obviously a massive discrepancy between Pan F+ and other Ilford (and Kodak) films in keeping properties. This isn't a general film problem, it's a Pan F+ problem.
Happy photography times ahead, I hope!