Inkpad 4 and the system ebook viewer

[gillesit]

Since I'm not an English speaker, I'm using a translator, hoping you can understand what I'm writing.
Hi everyone, I've had an Inkpad 4 for about a month and I'm quite happy with it. When using the system ebook viewer, I notice a few things, like this. When opening the ebook, sometimes three dots appear in the middle of the bottom where the "page number/total pages" normally is, plus another larger one that scrolls back and forth over the smaller ones. This sometimes lasts a couple of minutes or longer. Is it the page count recalculated after, for example, increasing the font size? If this doesn't happen, for a while I see a small hourglass in the bottom left of the reader and I don't understand what it does. I've disabled both Wi-Fi and Bluetooth and I don't use the sync feature. Do these two things happen to you too? I tried using Koreader, which is a step up from the system reader, but it has too many features/settings and I'm only interested in reading.