After I migrated our Connections from 5 CR3 to 5.5 some of the blog images were missing.
Resolving the issue:
Step 1: compare the [ConnectionsData]shared/blogs directory on both servers.
Compare a single blog you could just need to know the ID. for example 4b399954-c36a-4b8e-b281-0ad62937a83c. Then you would go to
[ConnectionsData]/shared/blogs/upload/4/b/3/4b399954-c36a-4b8e-b281-0ad62937a83c directory and compare the number of files
ls -l |wc -l
Source and migrated directory contained the same files.
Step 2: check if the missing pictures have umlaute or special characters.
if this is the case, then there might be the following line missing in .bashrc