When I apply the transition to a track, it is affecting the tracks too below the intended tracks also.
This issue was not there earlier.
Eg: If I have Video , Video 2, Video 3, Video 4 in order from bottom to top,
If I apply dissolve between Video 4 and 3, Video 1 and 2 also disappears in between for a second.
It started recently. Can anyone identify what is the issue?

Are you using Kdenlive for Windows or for Linux (what version?) your decimal separator is COMMA or POINT? (different country/states have different separator)