PTBes 60.b:54[2] :כמה דצרכת לרבנן קדמאיי וקשת בידיהון כן צרכת לרבנן אחריי{^א^} וקשת בידיהון‏ : just as it was in doubt to the earlier Rabbis and remained difficult for them, so was it in doubt for the latter Rabbis and remained difficult for them
See the entire entry for qšy vb. to be difficult