Thanks! It is also strange that once I have booted slot B (in twrp) I lost root and twrp ...
Will flash twrp tonight and see try flash the recovery zip you mention.
If you're on the newest May factory image with the May bootloader you're going to have to flash chainfire's V3 zip whenever you flash TWRP, SuperSU, or you will lose TWRP and probably loop.
Golf c gave me this guide worked great with su and magisk
to update to May firmware with May bootloader this is how I did it first install may factory firmware with April bootloader's then install your rom and set it up. And root. Then after you root * boot to system. Boot TWRP and install v3 zip. Then Reboot to bootloader and install may bootloader's. Both slots. Then Reboot to system. Good to go. Just remember to flash that v3 zip after you alter boot, like TWRP,magisk,kernel.
You may not have to flash both slots but I did because I have my phone set up that way.