i really have no clue bud. i havnt had that happen and havnt heard of it happening to anyone else yet.
what software version were you on before you flashed lineage? I was on v20k and the kernel and firmware in this rom are based off of v20k. If I were you I would try to find the v20k kdz and use LGUP to flash it, see if you can use the refurbish setting instead of upgrade, but obviously do whichever one it lets you. remember, i did say in the OP that you should probably be on v20k to avoid issues since I havnt had any being on that version before I flashed.
while your in the stock rom backup you took, you should use adb and see if /firmware/image/ exists and make sure that wcnss.b0* and wcnss.mdt exist. there should be like six entries in there that say wcnss.something. if they arent there, that could be the issue since those are firmware files for bluetooth and wifi and you might have to take them from lineage or another stock rom and place them there or in /vendor/firmware/ after making an insecure boot image for your stock rom that lets you remount system as rw.