Sudden Drop in Indexed Pages and Images under Sitemap

[Bibliotek123]

Hello! Just a couple days back, realised that under the Google Webmaster Tool > Sitemap, my website www.bibliotek.co has a sudden drop in indexed pages and images. Previously, it was almost fully indexed. However, I checked and the Google Index > Index Status, it is still fully indexed Any reason why and how do I resolve? Any help is very much appreciated!

Thanks in advance!

[slatronica]

I see your site is running SSL - are you sure you are looking at a search console profile setup for https? Is the sitemap submitting https now after a switch or vice versa?