the very same is here with me, problem was started from august 2019, till august it was working fine without any problem. last time when google read it there was a total number of 244000 urls from different sitemaps in the index file were showing as discovered. after that i noticed that 'last read time' was updated daily but there was no change in the number of urls as it was not showing new sitemaps in that list in the index file.
so i resubmitted that index file... and now the picture was 99% similar to the original question with a difference that total discovered urls are still 244000, but sitemaps read section is not showing any sitemap there
so now i changed the name of sitemap index file and submitted it again with a different name and now the picture becomes 100% similar to the original question, index read success, 0 discovered urls and everything else
I searched a lot on internet to solve it without any success. If i am giving an answer here that means i am still looking for it
still there is no issue with other search engines as they are reading it perfectly.
So my answer will not satisfy your question but unfortunately that is a bug in new GSC as it came with lots of bugs and no one is there to solve them.
If someone has found something else its a most welcome