Why my progress bar never reaches 100 percent

This is very likely due to the fact that you have unedited fuzzy matches or unedited machine translation (MT) matches in your document. In order to move the progress bar, unedited fuzzy or MT matches need to be "verified" using the Verify Segment icon under the Translation tab, its shortcut, or by clicking on the green check mark in the far right column of the segment.

Here is a short video that explains how Verify Segment works.