AO Her in 2021 and anomaly in visual observations

Prompted by BAA VSS Circular No. 196, I checked the past light curve of the R CrB star AO Her. The observations by two most prominent visual observers around the 2021 fading did not agree at all with CCD observations. They (and also Jose Ripero, as I suggested in vsnet-alert regarding other objects) didn't notice the start of the July-Aug. fading for more than two weeks. They reported unreal fading in Apr.-June. They also didn't notice the brightening in the later half of 2020. The reported values, however, agreed very well between these observers (but no correlation with CCD observations). A naive interpretation of this strange phenomenon would be that these observers were copying other persons' observations each other. They were not correlated with actual variations and researchers should pay attention when using any database (e.g. AAVSO) containing observations of these observers.

Of course, I had noticed the sign from the past (already in 1996 in V705 Cas, which was interpreted as a "telephone effect" by Gary Poyner if I remember correctly), but the present case and other cases are too apparent with sufficient evidence in the presence of modern CCD data.