Before you start any major search for issues and bugs, I would highly recommend to update to the latest version (LTS Release 3.28.47) and see if the problem persists. I don't think it makes sense to research for issues in a version of LS that is at least over 2 years old (latest version of 3.24.x was LS 3.24.6 build 201109, so it was released on 09.11.2020.
(
community.limesurvey.org/release/201109/
). As you didn't provide the full build number this is the latest date.
A lot of things can have happened since then. You might also want to have a look into the release notes and see if it mentions anything about a bug fix that sounds like your problem, from your version to the lastet version.
But I think, before you do anything else, do an update. You should make updates on a regular basis anyway. 2-3 years can include a lot of changes.