My tube lose air once inside Tyre and mounted on wheel? I am getting this weird experience.My tube holds the air when removed from wheel and tyre but lose it once in tyre mounted on wheel.I removed it 4 times and checked for bubbles in water bucket.No puncture.Air holds even for days out side wheel and once it is inserted in Tyre ,mounted on wheel and pumped the air,it lose in a min .What could be the reason?Some ghost/spirit playing games?I am really puzzled .
Check the rim for protrusions - is the rim tape misaligned?  Are there any lumps/bumps?  Any spoke ends prodruding just a bit too far?

Check the inside of the tyre/tire for lumps and bumps too.

Are you using a presta valve in a schrader-sized rim hole?  Could be opening a small hole there when pressurising.

Do you always put the tube in the same way around?   Try flipping it to move any weak point around.

Hmm - "weak point"  raises a thought...  Perhaps you should cut your losses and just fit a new tube.  They're consumable; I guess your current one has done its dash.   Don't want the weak point to turn into a blowout.