Why do I have to restart my iphone to get photos onto my computer?

This is pretty recent - maybe a few months duration. I haven't updated my OS (Yosemite 10.10.5) but I have updated iOS (11.2.5, iPhone 5S) and I think the last update was when this started happening (so I'm leery of updating to 11.2.6). When I connect my phone to my computer to download my latest photos, Photos opens as usual, but it says there are no photos to import - which is not true. The only way to get it to work is to restart the phone. This happens every time now. What's going on? Is there any way to make it work right?