SQS resource connection - connection "working", but can't send a message

Hi there!
I am building an app that should send a message to an SQS queue when user clicks a button.

I've setup the SQS connection and it shows up in green, working, and it shows me a correct list of available queues.

However, when I try to do a resource query to send a message to the selected queue, I get a 400 error from AWS saying "the specified queue does not exist"

I am using AWS secret and key. The user has full SQS access. I've checked the queue url, it is correct and it contains a correct region.
The queue is a FIFO queue, but I've tried with non-FIFO queue and the result was the same. The contents of the message don't seem to matter. I am on non-prod environment, and no firewall etc here.

Any ideas what else can it be? Any help would be appreciated!