Mp4Box - Output is generated without frame Width, frame height & frame rate

[Saptarshi]

HELP| Please refer to attachment for better understanding. Thanks

•> I have two files pup1.mp4 and Pup2.mp4

File properties >


•> I wish to concatenate them (using mp4box) and create pupOP.mp4

•> BUT when I run the following command the Output (pupOP.mp4) is generated without frame Width, frame height & frame rates

!!ISSUE!! •> THE file plays (only in rare players like POT player) BUT it lags smoothness and the thumbnail in windows system are not shown while compared to its parents (pup1.mp4 and Pup2.mp4)
!!ISSUE!! •> Also, it is not being accepted by online video streaming services.
!!ISSUE!! •> I tried to reconvert (with intention of repairing) it using Handbrake BUT it gave the following error


HOWEVER, when I try to use the same file twice or more (as parents, i.e. pup1.mp4 & pup1.mp4…) this works well, and NONE of the above issues come! Please check below


Kindly help with the solution, how to make mp4box output of concatenating multiple different .mp4 files to bring robust and concrete?

THANKS IN ADVANCE!!