Your expectation that if what climate scientists are saying is true then temperatures should rise in lockstep with changes in CO2 levels is unrealistic. Over the short run (less than around 30 years) other factors can override the slow but steady underlying signal of warming from CO2 and other greenhouse gases.
For instance during and after WW II there was a massive increase in industrialization with little in the way of pollution controls. That dumped a lot of aerosols into the atmosphere which reflected a lot of sunlight before it could reach the surface. Beginning in the late 1960's we instituted pollution controls that reduced the problem allowing the underlying signal to take over again. The industrialization of China and SE Asia over the past couple decades has had similar effects and they have yet to institute effective pollution controls.
Other natural factors that can affect the global warming signal on the short term include volcanoes (there was a measurable cooling effect from the eruption of Mt. Pinatubo in 1991), changes in the oceans (where over 90% of the heat from global warming goes) such as ENSO and the PDO.
Just because the temperature record doesn't show a steady rise in lockstep with CO2 rises doesn't mean the underlying signal isn't there.
As far as the IPCC report goes you need to dig deeper. The details are ultimately in the thousands of scientific papers cited by the report. The summaries are edited by politicians but the WG 1 report itself is written by scientists. They simplify their presentation to make it more accessible to non-scientists but as I say the real details are in the cited scientific papers.