Were the results showing before?
Nothing on the backend area is saving, or only the custom post types? Is there any error code showing up in the search bar?
You should try disabling all plugins and switching the theme to default to see if it works then. If not, then it's most likely an incompatibility with the server configuration. If yes, then it's a plugin/theme interference.
Never encountered this issue before, so this might be a new bug or something else.Best,
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