Yes, Frontier changed something about the API that caused imports to stop working, although it's kind of a weird situation:
When a third-party app (like EDSY) is using Frontier's authorization system to request player account information, the app has to specify which "scopes" of information it wants. For ED the options are basically "character" (your Commander's name, location, assets, active ship, etc) and/or "player" (your real name, email address). EDSY has no need for your personal information and I want no responsibility for EDSY having to receive it (even if it's just discarded and not stored or used for anything) so it's always only requested "character" information.
However, for a long time (probably since that third-party auth flow was first introduced), Frontier's API has been sending personal "player" information all the time, even if the third-party app didn't ask for it. We (various app developers) notified them about this several times, but it was never fixed. Instead, about a year ago, the API just started rejecting requests that only asked for "character" data. In order for the API to return anything, we are now required to ask for personal "player" data even if we don't need or want it.
So far, I've opted not to do that, since I think it's a very poor security practice on their end and there is a viable alternative via your local journal file (for PC at least, and console was dropped by Frontier anyway). I've left the API import feature enabled hoping that Frontier would eventually fix the problem correctly and then it would just start working again, but at this point maybe I should just disable API import with a notice about why it doesn't work any more.
Also, FWIW, you can drag and drop a journal file onto anywhere in the EDSY window at any time, you don't have to open the Import prompt first. There's also a way to give EDSY a journal to import directly from a web request, which some other desktop applications (EDMC at least, I think?) use to make it easier to find your journal file for you and upload it.