Up until the last release I was happily running "separate" instances on MatterControl 2.0, The latest upgrade appears to not support that. I am adding multiple printers to the 2.19 version and getting tabs for each printer. I have three Anycubic i3 Megas and 1 Anycubic Delta.
bug 1) Printing is not an issue except for the incorrect flashing tab when I add a STL to the last selected printer tab (it always flashes the first tab), but at least puts the part on the right printer.
bug 2) when I go to slice, I am never sure that the right slicing tab is open though because the right tabs do not refresh. I usually end up re-selecting the printer tabs so I can end on the one I need.
bug 3) when I have to reboot and restart everything, I find that the wrong printer tab gets created even though I selected the correct printer from the list. I have named my printers Other Prusa i3 #1 com4, Other Prusa i3 #2 com12, etc. It may not happen on the first printer, but it did happen on the 3rd printer when I was going to connect so I could do some maintenance on it. I selected my Other Prusa i3 #3 com13, and it opened the #2 printer. I was printing with that printer at the time and had two tabs for the same one. It didn't connect at least, but I have seen two tabs disappear when deleting the same named printer at times.
bug 4) I may be missing something, but I would love dearly to clone a printer and keep a master, so I can update my other two printers. The slicing and printing options could be shared and it would make life easier.
That is it for the moment. I did want to say that I am able to do the printing I need to do and am in general impressed with what MatterControl can do. I just need to have it be more stable in the multiple printer scenario.