As seen in user reports, getting a new IMEI to "stick" using QPST or QFIL on an LG G8 is notoriously difficult. A wrong move can permanently damage the phone.
Most technicians utilize dedicated service tools to rewrite or repair the IMEI when it has been corrupted (often showing as "0" or "Unknown"): lg g8 imei repair
Modifying system files without backing up security partitions often leads to an IMEI status of "Unknown" or "00000000000000." As seen in user reports, getting a new
This approach requires more technical expertise: As seen in user reports
What is the exact of your LG G8? (e.g., G820UM, G820TM)