Image not refreshing in habdroid and 3house, works in browser

I have setup a small test image refresh (public traffic webcam with no authentication):

Image url=“” label=“Cam” refresh=4000

Openhab is 1.8.2 and has authentication. Accessing via http in browser works fine (both inside and outside of my home network), with image being updated as expected. However habdroid shows the image, but does not refresh it (nither inside nor outside the home network). I have to manually change page or clear image cache to trigger a refresh. 3house client on android also does not refresh the image. What am I missing?