Greetings martineau4444,
Let's check to see if the issue may be connection related. Though the computer does appear to be wirelessly connected to the EOS M50 camera, let's check to see if there is an active VPN service or software running on the computer. This may interfere with how the computer communicates with the camera. If it's active, then let's disable it prior to connecting the computer to the camera's access point.
Similarly, if the camera is connected to a local wireless router instead of it using it's camera access point, then traffic and bandwidth on the wireless router may cause picture and video transfer issues from the camera to the computer. There may be other devices on the network that are using the bandwidth for data transfer. If the camera is connected to a local wireless network, then please use the camera's access point since this would eliminate any issues of other devices being on the network aside from your computer.
The camera may have trouble transferring large files. In case you are trying to transfer a large video file then let's test to see if transferring a small file will work. You may record a sample video clip that's about 5-10 seconds long and see if that video file will transfer. In case it does, then we recommend on using a USB cable to download the larger video file, or using a memory card reader.
