No, It's not a problem with any flags, it's a general problem with VSTis not working in the XM format. Since this has been the case since like forever, there are two possible things to do:
- Remove VSTi support from XM alltogether (that's what I prefer)
- Fix it
Please solution #1.
You are a compatibility driven person. I would go even fas as: VSTi "support" (together with all the non legacy extras) should be removed from all the legacy module formats. Including our new "hacked" .IT format. These hacked modules are only playable with ompt only anyway, if you try to load a vsti extended song to a normal, .IT compatible tracker or player, it will fail to play, or in the worst cases even fail to load. Basically we're speaking about format features and standards that every related programs are following*.
Our special extended command list, channels, rows and all the plugins, other fixes, "hacks", etc. should strictly stay in the OMPT's native .MPTM format. Every other tracker is working* like this with the non legacy stuff, for an obvious reason.
*(or at least, we would expect that

)