Please deactivate all the plugins not related to the theme and switch the parent theme, check the issue, If the problem has gone, activate the plugins one by one, checking the issue to detect which one causes the problem.
if the problem remains, even after the plugins deactivated leave the plugins deactivated for us to check and provide your site admin access to the private area.
If you cannot keep the site without the plugins confirm the permit for us to deactivate the plugins for the while of checking what may take up to 15 minutes.
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