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https://sizamtheme.support-hub.io/articles/how-to-write-to-support-if-you-need-technical-help

PS
Are you sure that RH Frontend Pro is working properly after upgrading to WP 5.9? It doesn't work for us. The added meta fields (meta key) are not visible.

Thx.

Use actual theme version 17.6 and Rehub framework 16.1

After upgrading to WP 5.9 (unfortunately automatic on some hosting) it is not possible to save posts - no problem in other themes.