Unfortunately, I am still having the very same issue, and I am opening this thread to hopefully once and for all find a fix for this bug. Although the linked thread is useful, I will try to explain it here too, which hopefully makes it more clear.
The situation:
I have a listing website where people can post their house for sale. People can add a country, region, images, features of the house and text. The original website is Dutch, and I have successfully used WPML to translate the website to English. Since the content is user-added, this can mean that people can sell a house and insert a country and/or region that is not yet available in the other language, because it is the first. However, this is not per se the problem, I periodically check for new stuff and translate it to the other language.
The problem:
So, I have translated everything from Dutch to English. Let's take the taxonomies 'country' and 'label' as example. I have translated 'Nederland' to 'Netherlands', and 'Te Koop' to 'For Sale'. They show up in the appropriate columns in WordPress under Dutch and English/WPML respectively.
However, for some reason, the taxonomies get messed up over time (in around a week time, sometimes way less). The taxonomies get messed up in such a way, that the previous 'Netherlands' that was in the English/WPML column (when looking at it as admin), moved to the Dutch column, and 'Nederland-en' or 'Nederland-2' has been added in the English column with 0, 1 or 2 houses linked to it.
The result of this problem is that on the English/WPML website, Dutch labels are shown again for the taxonomies that got messed up.
How to solve:
The way I solve this again is by deleting all the English translations that wrongly ended up in the Dutch column, and deleting the new taxonomy that got added automatically at the English side ('Nederland-en or Nederland-2'). After this, I re-translate the Dutch/original taxonomy, and go the WPML --> Support --> Troubleshoot --> Syncronise post types for the category 'estates/houses'.
However, after some time this happens again and I have to redo this method to solve.
Steps to reproduce:
As stated in the previous thread too, I (and your colleague) did not find a way to reproduce why this happens. However, I think it may be due the fact that a new house is added with maybe a new taxonomy? Or maybe the sequence of publishing the house on the Dutch website first and then translating, or first translating and publishing on both the Dutch and the English website?
I just hope that with a new look and your expertise, maybe this issue can be found and hopefully fixed. Would you kindly look into this?
Thank you for your time and efforts. If you require any additional information, please do let me know.
The only way this could happen is if in some way new taxonomy was added, I do not see any other way would new taxonomy would appear. I am also pretty sure since this happens with default language taxonomy, it would happen also without WPML.
I suggest, that you to further check how are this new taxonomy being created/added, either via some log plugin/server log or try to investigate further via time of creation and etc.
For us to help further we would need to know how the issue happens, guessing and investigation without these steps would be really time-consuming.
I can also advise disabling Object cache and trying to check if the issue still happens since sometimes it can cause an issue with WPML.
Thank you for your response. When it comes to the countries, users are presented with a dropdown option with countries that currently exist. But could also type a country themselves. This could indeed lead to maybe two instances of a same country. I will disable this issue and see what happens.
However, this is not the case for other taxonomies. Some taxonomies are blocked from being added by users, and users can only choose from a pre-defined list. However, also with these taxonomies I see that taxonomies that exists before in the English column, have moved to the main/Dutch column over time.
I have disabled all plugins (including object cache) for a long time, but unfortunately it does not appear to be a problem with a specific plugin. Is there any other way to investigate this?
The best way to continue here would be to monitor when the issue happens and try to find the steps or actions that cause it. From there we would be able to check and debug the issue further.
I am afraid like this, without knowing how it happens, it would be almost impossible for us to know what to investigate further.
My random guess would be Object cache, sometimes it can cause such weird random issues. I would advise checking again and making sure it is OFF also from server side.
