Experienced the same problem. It only happens when I have some particular blueprints opened in the Blueprint Editor. Memory usage will start to grow by over 3GBs in under a minute. Closing the Blueprint causes RAM usage to go down again.
However, since this is a migrated project there were a truckload of tabs opened in the blueprint editor (I think enarly every function was open in a tab). I closed them all and opened only one and the RAM usage has been stable for now. I don’t know if it was the sheer number of open tabs or if it was a specific tab that was causing the leak. I’ll keep an eye on the RAM usage as I go through the BP’s function graphs.