Lines not connecting to magnets properly anymore

I’ve noticed that lines are not connecting properly to magnets on rectangles anymore. I’m convinced something is broken as I’ve used Omnigraffle for many years without this issue. The trouble started a few versions back and it’s just gotten worse.

Using Pro 7.12.1 (v198.5.0) on a 2017 Macbook Pro retina with Catalina 10.15.1

I’m using a UML class stencil where two rectangles are grouped together using the table command. The group has these Connections settings for Lines:
Allow connections from lines (check)
Connect to the group (selected)
3 magnets per side
Default object ranking

The line I am using for connecting:
Allow connections from lines (check)
Allow connections to other objects (check)
Allow shapes to become labels (check)
Route from object centers (unchecked) // I want to route to the magnets

Normally, I can just drag one end of the line to a magnet on one rectangle group and the other end of the line to a magnet on the other rectangle group and each end stays connected to its respective magnet. And, much of the time this works okay. But frequently I find that a line end simply refuses to connect to the magnet I drag to and instead either refuses to connect or jumps to some group elsewhere on the canvas. Infuriating!

Sometimes if I quit the application and restart the problem goes away. But, often it does not.
Can someone look into this?

(copying this message to support)

I am seeing this also. Happened after the Catalina upgrade.

I am also experiencing this problem. Some times it is just impossible to connect two UML Classes with a simple arrow from the same stencil.

I have to restart OmniGraffle to get it done. After I restart it, I can connect the two classes with a simple drag and drop of the arrow ending.

Having the same problem.

Restarting OmniGraffle corrects the problem, although it starts to happen again on different objects, requiring a lot of restarting.

Environment is OmniGraffle Pro 7.12.1, MacOS 10.15.2, MacBook Pro 15" Mid-2015 2.8 GHz i7 Dual Graphics and using an external monitor.

I am seeing the same thing. Restart helps it just a little while then magnets are not working again. Or only on some (unpredictable shapes). On Mojave here.

We’ve identified an issue with this after duplicating a table. This appears to be fixed in the 7.12.2 test builds if you want to give that a try. If you still encounter this bug please let us know and if possible, send us a copy of the file. Thank you!