Manual override zone volume ignored

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I'm a beginner-intermediate user of E+, I've been making some things work, so I am somewhat capable of shooting issues down as they appear on the error log, but I've come across this error that's baffling me.

As I draw thermal zones and save them, I find out that edges that enclose the zone come just a little apart making almost imperceptible gaps, so E+ can't calculate the volume anymore. Annoying. I read the severe warning on the error file, which for example says

** Severe  ** For zone: PLANTABAJA it is not possible to calculate the volume from the surrounding surfaces so either provide the volume value or define all the surfaces to fully enclose the zone.
** Warning ** Indicated Zone Volume <= 0.0 for Zone=PLANTABAJA
**   ~~~   ** The calculated Zone Volume was=0.00
**   ~~~   ** The simulation will continue with the Zone Volume set to 10.0 m3.
**   ~~~   ** ...use Output:Diagnostics,DisplayExtraWarnings; to show more details on individual zones.

So I tried manually overriding the volume values for the zone and I'm still getting the same warning, so I feel like E+ ignored what I did there. Any suggestions on what to try next?

(I'm using Windows10, Sketchup 2017, Legacy OpenStudio 8.7, IDF Editor 1.50a , EP 8.9.0)