Drag and drop problem after 3.5.1 installation

Since upgrading to DT 3.5.1 and Catalina 10.15.5, I am having trouble with drag and drop in text and RTF apps including TextEdit, Nisus Writer Pro, and even the notes in DevonThink. The problem is that there is a drop-down services menu that blocks the drag unless I am extremely fast in dragging before the little arrow appears next to the selection. This is not convenient. The reason I am bothering you with this is that the services menu is filled with a long list of DT services that could be convenient, but not as convenient as drag and drop. So I thought you might have a solution for me. Also at the top of the drop-down menu is the name of a little app called CleanText that I have now deleted but won’t go away. I’ll try to add a screen shot, but I fear it will be too big.

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The contextual menu only appears when you Control-click (or right-click).

" The contextual menu only appears when you Control-click (or right-click) ".

Yes, that’s the way it’s supposed to work. At the moment, I’m using a cheap, two button, wired mouse. I get a small menu with the left button, and a long one with the right. I have similar behavior with the Apple wireless mouse in one or two button mode.
The problem does not occur with Pages or Apple Mail. Curiouser and curiouser.

I was mistaken. I am getting the short rogue menu with both the left and the right button. The normal long menu appears only with the left button plus Control key.

Are you using a laptop or a desktop?
If a laptop, does it occur when using the trackpad?

Using standard iMac 27 manufactured 2017 with a lot of library left over from older Macs and systems.

I have solved the problem by running Clean My Mac.app. I hereby resolve to use a clean install with next major system upgrade.

Thanks for the follow-up.