The reinforcement of fused filament fabricated (FFF) components with continuous fibers allows for high versatility in the design of mechanical properties for a specific applications needs. However, the bonding quality between continuous fibers and the FFF matrix material has high impact on the overall performance of the composite. To investigate the bonding quality within additively manufactured (AM) continuous fiber reinforced specimens, tensile tests have been performed which revealed a sudden reduction in tensile stress, that most likely was not related to actual rupture of continuous fibers. Consequently, within this work we will expand upon these findings and present results of fast on-the-fly in-situ investigations performed on continuous carbon fiber reinforced specimens of the same AM build. During these investigations, specimens are loaded under the same conditions while fast XCT scans, with a total scan time of 12 seconds each, were performed consecutively. The resulting three-dimensional image data reveals internal meso- and macro-structural changes over time/strain to find the cause of the aforementioned reduction in tensile stress.