Background layers not visible

[peterdesmet]

Issue reported by Etienne Branquart over email:

FYI, it looks it is not possible anymore to visualise background layers of maps displayed on alert riparias:

I’m also wondering if the alert system still could be adapted/improved. One idea would be to highlight new observations on maps and/or alert emails that were done in sites/grid squares wherein no historical observation was done before, that may potentially require urgent action in the field. Does it look feasible?

@niconoe can you look into the missing background layers and answer Etienne by email regarding improvements?

[niconoe]

Note to self: after a quick check, the issue seeems CORS-related, and might be because we load OSM tiles overs HTTP while the rest of the site is HTTPS, to be investigated!

[niconoe]

Fixed!