How can I enable inner bleeds in InDesign? On the screenshot you see prime faces option, and 5mm bleeds. But, as marker on 2 red lines, I can't see this inner bleed, and as a result on bottom part of screenshot, it's a PDF preview in Adobe reader - the inner part of the image has an empty space.
To do this, go to the pages palette, and in the options drop-down, disable (uncheck) "Allow pages to shuffle" or disable "Allow selected spread to shuffle," and then you can drag the pages away from one another into "broken spreads" which will allow you to manipulate the bleed on all edges.
Below right: pages palette with a broken spread and full bleed all sides on pages 2-3; pages 4-5 have traditional bleed on outside (trim) edges only.
Below left: from PDF export using crop and bleed marks. Pages 2-3 have full bleed all sides; on pages 4-5 you can see the bleed at the spine/gutter consists of the content of the facing page.
When you're exporting that single, make sure that you have the 'Use Document Bleed Settings' option ticked, under the 'Marks and Bleeds' option tab.
Also it's a little difficult to tell by your screenshots, and I think a little is lost in translation, but some pdf readers (including Acrobat I think) will treat empty space as transparent and even crop it out. Make sure you're going right into that space with your image, or fill it with a white rectangle/similar.