Hello,
Thank you for contacting Rank Math and sorry for any inconvenience that might have been caused due to that.
This is odd behavior, I am able to enter and save images on Gutenberg when Rank Math is activated with no conflict. Could you please help us investigate whether your theme or one of your other installed plugins is not playing nicely with RM by performing these steps: https://rankmath.com/kb/check-plugin-conflicts/
Looking forward to helping you. Thank you.
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Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.