When a file is UTF-16 LE encoded the characters do not display correctly. It is also not possible to view diffs of these files. The interface incorrectly says that there are no differences.

Here is an example that I borrowed from BCLOUD-5648
https://bitbucket.org/EricFromCanada/ericfromcanada.bitbucket.org/src/55865a3ee2bf/applescript/close%20Safari%20Web%20Inspector.applescript

Looks like there was a similar issue in bitbucket server.
https://jira.atlassian.com/browse/BSERV-8501

Workaround:

• Use the Raw format in the UI to view the content of the file. They can use the ...(Three dots)->Open raw option to open the file in the raw format
• Convert the file to UTF-8 (Bitbucket supported format) locally and push it into the Bitbucket. They should be able to view the file in Bitbucket UI.