Trying to go tubeless with Fulcrum Zeros

[SwallowfieldOldy]

Aarrgghh! Having gone tubeless on my other bikes I thought this would be easy; but no. My set of Fulcrum Racing Zeros I bought in 2016 and love to use have a hole in the rim which I thought was for venting of the rim space and was not linked to the tyre bed. However, as fast as I pump up the tubless tyres, the air comes out of this hole. I always thought these wheels were designed for tubeless given the lack of spoke holes in the external rim.
Does anyone know a solution to this or am I incorrect in thinking these rims will take tubeless?
Here’s hoping.

 

[vickster]

Are they the 2-way fit version?
https://road.cc/content/buyers-guide/your-complete-guide-fulcrum-road-wheels-189404

 

[Pale Rider]

Can you tape over the hole?

It's obviously there for a reason, but it's hard to see what catastrophe may befall you if you block it.

 

[Milzy]

Should work TL as long as taped properly with the right tape.