[Moto G5 Questions & Answers] muttleytm:
I've had a MOTO G5 for several months at least. This issue came up recently as I was able use the USB connection notification to switch the phone to file transfer via USB with no problem. Everything worked. This notification no longer appears. The phone also does not show up on the PC at all.

I have tried numerous cables and different ports on the PC. I have also booted the computer up as Linux (which is what I normally use and the phone worked with) and I have also booted it up in Windows 10. The phone is not detected in either case nor does the notification appear. I have also connected it to another Windows 10 computer entirely and the phone is not connected. In all cases it I'm using USB1. They are all older computers and none have USB three and only one has USB 2 and USB 1, but, I use 1 generally, but, also tried 2. I don't know which version of USB cables are for. I've tried three data/charge cables and I think two of them are just for USB 1 and the other is new so might be rated for 3. I don't know.

I have installed the latest Windows drivers and the MTP drivers are all up to date when running Linux. In linux I have run some USB commands like usbls and none of them see this device.

I do know the phone has had a few updates including a security patch or some OS update recently. The computer at least when running Linux (Mint 18.2) has had some updates as well. I don't know exactly when the problem started as I don't transfer files all the time, but, the file transfer ceased functioning at some point after updates.

So I'm assuming the problem is software related, but, I think the micro USB port is mechanically attached to the motherboard and connects with a ribbon cable. I may try installing a new port, but, I don't think that is the problem.

I've contacted Motorola technical support. After about a week Q & A they responded that my phone was a UK model and I needed to talk the the UK support. I had them refer me so I wouldn't be starting over from scratch. They sent me a standard list of things to try which I did and responded to what happened. They then said their were elevating me to senior tech support staff. After several more days they said they heard back from the senior support staff that they don't support Linux. Throughout the entire thread and specifically in the reply about what to try and reporting back I included how it behave in both Linux and with Windows 10.

In looking through some other forums I see that this is an issue in some other phones as well, not just MOTOs and it may have to do with a security update that came with Android 8. Android 8 isn't available for this phone yet in the US, but, I'm thinking that maybe the latest security update for 7 has some things from the 8 patch. Maybe???

Does anyone have any knowledge of what might be the problem or the fix? I will continue to try to work with Motorola/Lenovo, but, I'm anticipating they will after some more discussion say it is an OS problem. I have seen that at least for this problem on some Google Pixel phones with a similar problem a place you can go to submit some log files to Google as part of a bug report. Is this something I can do on this phone as well.