This is as alva842 and Willem says a result of the first relaease of the 1.17f patch comeing with an editor for a later part of the game (the editor uses BIC version 3 which supports multiple strategies, but the gems itself does not)
This was corrected within 48 hours from the realease by both the release of an old editor (the correct one) and changing of all the downloads of the file. I didn't think there still were anyone using this incorrect editor this long after it got out

. I suggest that you upgrade to 1.29f, but if you for dsome reason doesn't want to do that (modem connection???) you shall still be able to find the correct editor for 1.17f somewhere on this site, or if Markos has sorted it out on Civfanatics. if you still can't fine It I think I have a copy of it somewher for test purposes. (I keep all patches just in case I need to go back to an old for a day or too. I do actually think that i have both versions of 1.17f and both 1.16f (yes theyu were two too, but only the default rules were different betwenn them.))