If the top video layer is close to the top of the timeline, then when I drag effects from the effect list (2nd monitor) onto a timeline clip, the effect will only "drop" properly if the mouse is over the lower half of the clip rectangle.
Dropping on clips on lower layers, or when the top layer is well below the top of the timeline, works fine - the clip will highlight for drop when the mouse is on the upper or lower half of the clip rectangle.
Halving the drop zone for effects makes working quickly more difficult.
This is with DR Studio 20 beta 2; I did not check to see if it applies to DR 19.
Video linked showing the behavior - look for the drop zone highlight around the clip as it appears/disappears.
PC Win 11 Pro, 64GB ram; NVidia 572.83; dual monitor; RTX 3080 (10GB); auto/CUDA processing mode; SSD cache, separate SSD for data; Davinci Studio