Thank you for replying.Some months ago I had set up a VM for building LOS 18.1 for the Tab 4 10 Plus. I now tried updating the code and then building the stuff again, but I'm now getting error messages I don't understand. So it looks like someone else having to provide the 18.1 builds. I can continue with the 17.1 until someone steps up and regularly provides builds for LOS 18.1 (or even 19). Sorry
I think the Dev. of the LOS 18.1 for x704F tablet had stopped updating the ROM. Please contact him to see if he is willing to let you update the monthly security patch for his ROM.
Regards.