I have used Ubuntu MATE 16.04 for some time now and both Synapse and Tilda have worked well. I have now recently installed Ubuntu Mate 18.04 and I'm having some problems with both programs. Synapse seems to work to start with, but after opening and closing the window (Ctrl+Space) a couple of times it doesn't allow me to type anything; I'm typing, but nothing shows up, and I can't search in any way. I can still click with the mouse though, so it's not completely locked.
A similar thing happens with Tilda when I cannot hide the terminal with the regular key binding. It pops up when I want it to, and I can type in it, but I cannot hide it again.
I have no idea why this is happening.