I use Eclipse/Sloeber since a long time. Meanwhile I know many traps, but your bad experience is very strange. I cannot help, because I have no idea, why that happens with your computer.
Until W10 I used Windows and fell in the trap to install Sloeber in my working environment a few directory levels below root. The reason for the following errors is the limit of the path length in Windows. But that was the only severe trap I remember.
When W10 came up I changed to Linux.
With Linux I could not flash the boards. I did not know, that you have to extra allow serial communication in Linux. Also there were some time-out problems, e.g. for using Arduino DUE I had to manually update the latest BOSSAC driver from GitHub.
Meanwhile I have many Arduino boards plugged via USB at the same time and I do not use the build in serial monitor of Sloeber but many instances of GtkTerm (started in Eclipse via Run->External Tools). So I can watch the behavior of many boards (in RF communication with each other) sending debug information via serial the same time.
My experience with Eclipse/Sloeber is very good and I am sorry, that I have no idea, why it does not work with your computer.
May be You get help here:
Good luck