in and out points ignored

Ive looked at other forum posts that came up in a search for this but not seeing my particular problem

I would expect the following functionality

select clip in cut or edit mode.
hit X and frame with in/out points
hit play and the timeline only plays from in to out and stops

Im finding the in/out points are just ignored and it is quite frustrating,
no matter what I do it ignores them and just plays through

additionally I consulted with a coleague of mine to see how to isolate a clip on playback

he said doubl click the cliip and it should isolate it also, this also doesnt work
I mean it seams like that clip is selected and the rest of the timeline is greyed out but it just continues to play the whole timeline

any thoughts as to what I am doing wrong?

best