For a while I was having an issue where the values for the first two inputs in the raster mosaic tool were not being carried over into the final product. This confused me for a couple hours and while I could find other people asking the same or similar questions online, I couldn't find anyone give a concrete answer into what was causing ity and most of the help threads were left unanswered.
I was able to find an answer to my specific issue, so I thought I would post both the problem, and the answer here to provide anyone with similar issues a potential solution.
The steps that I was taking are: Using the Create Raster Dataset tool I create an empty raster, see below.
I then use the Mosaic tool using the five rasters I wish to combine as the input rasters and the empty raster as my target raster, see below.
The resulting raster (while keeping the same shape as the five individual rasters) has lost the information for the first two rasters (sections 1 and 2) and it replaced all of the values with 0!
This pattern continues if you remove the two rasters where the information is lost and only include the upper three rasters. See below.