This is because the default setting of 'Synchronize Mosaic Dataset' tool does not recaculate the cell size range for stale items.
The term 'stale' means the original item in mosaic dataset could have changed in extent, band, stats, and other properties that may cause the MaxPS to be invalid. 'Synchronize Mosaic Dataset' tool resets the MaxPS to 0 if the 'Update Cell Size Ranges' option is turned off. This makes the stale item invisible.
Manually change the MaxPS value by editing the catalog table, or enable the 'Update with New Items' option in the 'Synchronize Mosaic Dataset' tool. By doing so, the 'Update Cell Size Ranges' option will also be enabled.