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If you'll look in the bottom left corner of the Inkscape window, you'll see info on the style of selected objects. (I think these are called the Style Indicators -- where you can look to see details about the style of selected object.) ("Style" includes anything about the appearance of an object -- color, opacity, stroke width, etc.) Notice the tiny spinbox labelled "O:" which has a value of 0 in your screenshot. This indicates that the object is fully transparent (i.e. invisible). 100 is fully opaque. You can change the opacity right there, if you like. Or it can be changed in the Fill and Stroke dialog (Object menu) as well.
Probably, the last time you drew something with the Ellipse or Rectangle tool, you later made them transparent. For some reason that has never been explained to me, and which I think is rather ridiculous, the default behavior of Inkscape is to give the style of every newly drawn object the same style as the last thing that was drawn with that particular tool. Most people don't know this, and I don't know who would ever expect such behavior. But even for those who have realized it, they probably don't remember what they did with Inkscape, the last time they used it. And they certainly can't predict the next time they will use that tool. The whole thing is absurd, imo.
But I'll stop there, before I get into a rant, lol. The bottom line, fortunately, is that behavior can be changed. Double-click on any tool, to open Inkscape Prefs to that tools's options. Draw something with that tool, and give it whatever color and opacity you want it to draw, every time you use it. Leave it selected, then click "This tool's own style" (or it's something close to that) in Inks Prefs. Then click "Take from selection". And that's it. Now your ellipses will always be drawn in whatever style you set.
Let us know if have any problems with that

Edit
PS - If anyone would like to write up an FAQ message about that, I'll add it to the FAQ topic (
viewtopic.php?f=5&t=2037). It's on my to-do list, but it keeps getting pushed back, lol.