Can Portal and Portal 2 timing be changed to when the crosshair appears, it only makes sense because that's how the game is suppose to be timed, Half-Life starts on loading map c1a0 which is the correct way but half-life 2 isn't after map d1_trainstation_01, timing for all games was after first map load but Half-Life 2 starts on train honk so there is no reason for Portal to be timed different if every game isn't timed on map load and seems there are no active Portal mods/supermods to change the rules currently.
please note that I am only trying to point out something that is obvious to a fellow Portal speedrunner
Try checking in Source_Upack > portal > maps and make sure testchmb_a_02.bsp is there and if that doesn't work check Source_Unpack > portal > maplist.txt and make sure that testchmb_a_02 is in the correct place (underneath 00 and 01) and if none of those work ask in the discord or just reinstall the game