problem with non drop & drop frame rate timceocdes

This is the first time I am posting on the forums.
I am currently having a lot of trouble with non-drop & drop frame rate timecodes.
My documentary was 50.47 mins in drop frame rate. But my composer asked me to change it to non-drop frame rate as the sound wasn't getting synced. so we are actually going to do the whole sound again but I am having trouble with converting it to the non-drop frame rate. I have converted the documentary to non-drop but instead of it increasing its frames. it has shrunk my timecode by 3 secs but when i play the video everything appears synced but then when is my timecode showing me 01:50:44:01 while the length of the video is 50:47:20.
Is this normal ? can someone please suggest how to export my video or what should be done in this sitaution

And as soon as I convert my video from drop to non drop, suddenly the timeline goes to 59:56:12 rather than starting at 01:00:00:00
Can someone please help me. I am panicking.
EDIT [moved from Fotum Comments to correct product forum – moderator]
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