I found that beer yeast and champagne yeast hate baking soda, but bread yeast was fine with baking soda. Brewing yeasts take acidity better, and so the basic conditions of the baking soda must be too much for them.
Also, be sure that there is no water in the line. Sometimes if just a little gas gets started producing, but not at a good rate, the water from the aquarium gets drawn up the airline as the water absorbs the CO2. Once the water is above the rim of the aquarium, it can fill the line if the generator is below the aquarium already. So, don't put the generator under the aquarium until it is going well.
If there is any water in the line, shake it and tap on it and chase it back to the aquarium. Sometimes this is all it takes to remove that back pressure and let the stuff get going into the tank.
But, usually, it is a leak. To test for that, submerge the whole thing under water and be patient, wait 5 minutes before you give up and declare no leaks.