So after installing OPSS28.85-17-6 I had the issue below and followed the steps from earlier in the post:
On soak test 2 or later, I have my IMEI but no signal. What can I do?
In all cases where this has happened, the user's phone has relied upon an EFS backup for IMEI, due to flashing another persist. In these cases, it appears that the only way to get a signal is to use the firmware (i.e. modem, fsg, dsp - refer previous FAQ) from soak test 1. We're probably seeing here that the EFS does in fact need to be recreated to be valid. Unfortunately for these users, by not having their own persist, they are stuck with an old EFS and the newer firmwares appear to not work.
To do this
if you are already on Soak Test 2 or later, download the Soak Test 1 firmware download at either of these links:
Android File Host - oreo-soak1-firmware.zip
Dropbox - oreo-soak1-firmware.zip
If you are on Soak Test 1, install Soak Test 2 or later / official aroma installer and de-select firmware
Everything seems to be working OK at this point but will I be able to install future updates? How will this affect me going forward? Also, if I just want to go back to completely stock with OTA updates can I do that?