PSA if you have updated to 4.2.13:
There is an issue when using CTRL + LMB to disconnect a pin. I have submitted a fix for this, should be out in a few days.
In the meantime you can fix this issue by going to Editor Preferences > Blueprint Assist Editor Features and changing the hotkeys to CTRL + ALT + LMB / RMB like shown below:
Be careful not to remove the all the modifier keys, as this can cause issues (also fixed in the next update) you may need to manually fix your ini file to resolve this.
