The problem is created when syncing the pictures from Lr Classig to Lr Mobile. During that process they will get an "upload time / create time", but as Lr mobile sort them according to the capture date you will not see this problem until you create a web gallery. There they are presented in the same order as they were uploaded to Lr Mobile!
The work around is to update the sort order in the web gallery to capture date.
As soon as the support representative and I understood the reason for the problem she said that this will be corrected soon!.
This item is reported as Adobe Case ADB-19651987-L9V5