"rounding" issue with large number using BandMath

I’ve tried to use the BandMath(X) applications for a simple addition resulting in a large integer (9 digits). However the result is truncated by multiples of 4 (as if they were rounded by the closest multiple of 4). My image is a .tif (uint32) and I’ve tried different output type (uint32, float, double) without success. Any idea on how to avoid the rounding ? Even with the simple expression below it doesn’t work.

-exp “im1b1*100000 + im2b1”

where im1b1 is smaller that 10000

Configuration setup

My system: Linux
Version of the OTB: 7.2 & 6.7
**I installed the OTB with- the SuperBuild