When I add a custom basemap with URL 'https://example.com/tms/{z}/{x}/{y}.png' the value in the input box is transformed to https://example.com/tms/%7Bz%7D/%7Bx%7D/%7By%7D.png. I see network requests to that incorrect transformed value.
This fixes it: localStorage.setItem("customBasemapSources", JSON.stringify(JSON.parse(localStorage.getItem("customBasemapSources")).map(v=>({...v, url: decodeURIComponent(v.url)}))))
I suspect you are parsing the input as a URL.
When I add a custom basemap with URL 'https://example.com/tms/{z}/{x}/{y}.png' the value in the input box is transformed to https://example.com/tms/%7Bz%7D/%7Bx%7D/%7By%7D.png. I see network requests to that incorrect transformed value.
This fixes it:
localStorage.setItem("customBasemapSources", JSON.stringify(JSON.parse(localStorage.getItem("customBasemapSources")).map(v=>({...v, url: decodeURIComponent(v.url)}))))I suspect you are parsing the input as a URL.