You might be drawing too much current from the power source. Try disconnecting the LED strip and reduce the current limit before plugging it back in.
In order to simplify usage, the device will not require successful power delivery negotiation from the power source before it activates the LED strip. Additionally, the board will use the current limiting provided by the WLED firmware and you can easily configure WLED to draw much more current than the source can provide. In the vast majority of cases, this will lead to the USB Power source's voltage dropping or its over current protection kicking in, which then will lead to the system briefly shutting down before restarting again.