Stinky Shower Dilemma

[Robert Biggins]

Greetings BP Family, I hope all is well for everyone!

So, with the current home that I reside in, my plan is to transfer it to a rental property since I will be relocating to a different state for work related purposes.  The home itself is in great condition.  However, there is one annoying problem with the master shower; it reeks a stinky sewer smell after taking a nice hot shower.  We purchased the home in 2017 and everything was fine.  No smell whatsoever.  Just recently within the past few months this year (2020) we noticed a weird odor, not knowing where it came from at first.  Suddenly we realized it was the from the shower drain.  

A total of four plumbers looked at the situation and provided their recommendations.  The first suggestion was to demolish and rebuild the shower pan and plumbing system, presuming that the p-trap was not properly built to prevent the smell from rising up through the shower drain.  One of the plumbers suggested a shower pan test, and it passed.  A different plumber actually utilized a snake camera to visually check the alignment of the drain system and it was properly built, including the p-trap.  Using the baking soda and vinegar trick lasted for a brief time frame but then the foul smell reappeared.  Basically I don't want this to be a nuisance to future tenants.  We've been attempting to discover a permanent resolution.  Other than exhausting thousands of dollars to rebuild the plumbing system, would anyone have suggestions/recommendations for this situation?  Has anyone been through this plumbing ordeal before?