Error messages within index table creation are usually caused by errors during executing shortcodes within contents. Server Error 403 however might be different, or a combination of shortcode issues and some sort of overload.
This is almost impossible to debug without actually accessing the files, but as first step I would recommend changing the following options:
– Post limit per iteration to 4 or lower: https://i.imgur.com/Rvse5Zi.png
– Make sure that the Extract iframe contents and Execute shortcodes option is turned OFF: https://i.imgur.com/riBe4Ma.png
If there was an overload or a problematic shortcode, this may work.Best,
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