Bluetooth to JBL - always need to reconnect

When I want to connect my phone to a JBL music box (flip 5) that I was already connected with earlier, I first need to remove the device and then search for it again - connecting to it from the list of previous devices doesn’t work. This problem doesn’t show up for any of my other bluetooth devices, it’s only the JBL box - does anyone have an idea why this happens?