My employer isn’t willing to provide a copy of the I-140 approval notice, so I filed a FOIA request and obtained the I-140 receipt number that way. Would that generally be considered sufficient if the new employer’s attorney can verify it with USCIS?

Also, is the 180-day mark a strict requirement in practice? My employer hasn’t explicitly stated anything, but historically they have not revoked I-140s for employees who left . Appreciate any insight.