After uploading images we do not get the loaded image but the looking glass with minus sign, any thoughts, please?
This symbol means that the image cannot be found. This is most often seen on DEV, STAGE or PRE-PROD instances, where the images are not applied.
For the sake of time and space, when a production database is restored to another environment (DEV, STG), the images are not included in the restore/refresh procedure.
Because of this, when the system is brought online for testing, where there were images visible in Production, there is a - symbol visible on the non-prod instance.
If this question is specific to a production environment, please provide more detail so we can better answer your question.