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WARNING: Large total lw optical depth of ...

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hi, I am trying to add anthropogenic emissions mainly SO2, OC, and BC emissions using NASA HTAP inventory. The data is ingested fine in WRF Chem but in certain months of my simulations, I get very high AOD (all wavelength) values eg. X+26, in most grid cells. I update the inventory monthly. For some months, simulated AOD values are realistic. I checked the inventory and there is nothing I can find. In my simulation rsl log I get some warning though: WARNING: Large total lw optical depth of XXX at point XXX. As instructed in WRF Chem website FAQs, I had to increase the refr and refi values to a very high value (40) from the default value of 10. Earlier when I was only simulating dust, I had no problems, all AOD values were realistic. Now I am turning aerosol chemistry and photolysis and then I am having this problem. Anyone there to help please?
For the reader's benefit, I was unable to trace the exact source of this error but I found a way to deal with this. We should not ignore the warning message in the error log: "WARNING: Large total lw optical depth of .. at XXX grid points". This error is true for SW optical depth as well although it is not displayed as warning. This problem gets solved if we turn off the gas phase chemistry (gaschem_onoff = 0). In my case, turning off this was not intended because sulfate and other aerosols depend upon gas phase chemistry for their generation. So upon further investigation, I found that the error originates in d02 domain only. So I decided to turn off the gas chemistry in second domain only. I suspect there is some bug that is causing this error although I was unable to trace it.