With manual updates, depending how you do it, sometimes not all files are transferred to the computer (sometimes FTP transfer skips a couple of files). This could be one of the reasons.
I personally would probably update to the latest version LS 6.3.7 and make sure that all files are transferred and then see what happens.
Help us to help you!
Provide your LS version and where it is installed (own server, uni/employer, SaaS hosting, etc.).
Always provide a LSS file (not LSQ or LSG).
Note: I answer at this forum in my spare time, I'm not a LimeSurvey GmbH employee.
