How to fix a slight draught on my new french doors?

I recently moved into a new house and in the kitchen i have double opening french doors.
during this cold weather in UK the kitchen is extremely cold at night time due to a slight draught coming in through the vertical door sealant between the 2 doors.
There's no visable gap but can physically feel the cold air when you pass yur hand past. Any ideas to fix this?? Note: I did get a re-instalaltion of a sealing strip 2 months ago but problem still occurs.