Your site could not complete a loopback request

Hello,

I found that when I activate the plugin and go to site health in wordpress I get this error: Your site could not complete a loopback request

I narrowed it down to this plugin because:
If I disable ALL plugins – no error
If I disable ALL plugins but activate only WooCommerce – no error
If I disable ALL plugins but activate only WooCommerce and MultiCurrency plugin – loopback request error

Please advise! Thank you,

Best wishes,
Christian