After further troubleshooting I found that the issue here is caused only when the Post slug of the original and translated content is the same.
However I test this further in my test site it works fine there even when the slug is same. So the issue seems to be specific to your site and most probably is caused due to interference from third-party plugins or theme.
To find what is causing the issue you might need to do a conflict test or run the following tests:
- Backup the site completely or test this on a staging site to prevent any data loss or issues.
- Deactivate all plugins except WPML and CPT UI for a moment and activate a default theme like twenty twenty one then see if the post works fine.
- If yes, activate original theme and plugins one at a time and test each time to see which one causes the issue.
Also, to solve the issue by using different Slugs for translations in the mean time please follow the following steps:
- Backup the site completely first to prevent any issues.
- Go to WPML -> Settings page and scroll to "Translated documents options" section.
- Set Page URL option to: " Translate (this will include the slug in the translation and not create it automatically from the title)" and save.
- Edit the VINI post with the issue in main language and update by adding an extra space or character in the title or content to trigger a translation update.
- Edit the Translation and while translating set or translate the text for "URL" to something different than the original one as shown in the screenshot attached and complete the translation.
