Portfolio pages have 404 error because of polylang

On our homepage is a portfolio with manufacturer logos linking to individual portfolio pages. It is a German website that has been translated into English using Polylang. Every one or two days the portfolio pages are suddenly no longer accessible and show a 404 error. If we save the permalinks again without changing anything, it works again for another one or two days. If we deactivate the Polylang plugin, it also works again. This problem never occurs with the portfolio on the translated English homepage.

Does anyone know how we can solve this problem?

WordPress: 6.2.2
Avada: 7.11.2
Server: Apache
Server architecture: Linux 3.10.0-1160.95.1.el7.x86_64 x86_64
PHP: 7.4.33
Polylang: 3.4.5

Thanks for any help!
Tobias

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