Thanks for the response wichitpilot. Your settings and situation is quite similar to mine. Perhaps I could try and up the RPM and Feedrate to yours and see if it makes a difference. To improve plunging I changed the setting in Estlcam to plunge at an angle.
My only concern is why the problem happened after it went through the material, there were no issues for 4 passes and then once it managed to break through it got stuck in the wood!
I think trochoidal would probably make it a lot easier and smoother but I first need to understand why is it not happening as it is now.