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We're actively looking into this issue. So far, most all of the reports we're getting seem to be coming from Turkey, so it appears to be somewhat localized. Some affected users have been able to fix this by either switching Windows to using English, or, in one case, installing the Turkish language pack, making Windows Turkish, removing the pack, and then using English again fixed things. Could you try some of those steps and see if they fix you?
I can confirm that my Windows is localized in Turkish. However, changing Windows display language is impossible. The only option I have is Turkish.
Maybe this helps? https://support.microsoft.com/en-us/help/4496404#language_pack
Here is an interesting information. As you can see from this image the capital i letters are no longer displayed. In Turkish language there is a special character for capital i letter (İ) and it seems that the client is no longer able to display it after the patch. It is likely the problem is a charset issue and whenever a card is played that contains the capital i letter (İ), the game repeatedly displays an Asset Error Warning.
I hope this information helps.
Thanks for the info; we're running along similar lines and trying to understand how the issues around different capital 'I's could lead to the asset errors that are preventing play. We'll post more info as we find it.