i have this same problem except they actually do have ammo, they also use artillery from one of the other ve mods

Ditto, Still getting sieges spawning with mortars.

Was this ever resolved? Getting the same problem

To fix the artillery issue, make sure you have VE - Security after medieval in the load order

As for the mortar issue, Ive run into this in the past but im not sure if this is the case, what storyteller are you using?
I may be wrong but I think Sieges go medieval only when using Maynard

I'm getting this problem as well. Maynard is my storyteller. VE - Security is after Medieval in the load order.

I'm in the same boat as all of you, and can confirm Renzocooken's statement. VE Security is after medieval, got the artillery.

A way to get around this is to use the "Remove X Stuff" mods. Like remove industrial stuff and remove spacer stuff mods. They will remove them 100 %, although im unsure if seiges spawn at all with those mods, dont see why not though.

I'm fairly sure this is an issue with the mod itself and not a mod conflict, done a clean wipe of my Rimworld files and ran the medieval mod by itself with the security mod loaded after it and they still will only use Artillery or mortars, never catapults

At this point, I would like someone to point me to a mod that disables sieges only for the medieval faction

I don't think there is one and the mod author doesn't seem interested in giving us the option for some reason, even though I'm pretty sure it should be relatively simple to disable them.

Mod order is correct; disabling every faction except medieval ones still has medieval mortar sieges. Gone through a lot of pages of comments, and these posts, and haven't found a fix any where. Or, even really a talk about a fix. Just a comment from Oskar to someone that it's obv a bug and not intentional.

Here is the solution:

In 1.3\Patches\Self\FactionDefs\Factions_Misc.xml
Change
<li Class="PatchOperationAdd"><xpath>/Defs/FactionDef[@Name="VFEM_MedievalFactionBase"]/modExtensions/li[@Class="VFECore.FactionDefExtension"]</xpath>
<value>
<siegeParameterSet>VFEM_Medieval</siegeParameterSet>
</value>
</li>

to

<li Class="PatchOperationAdd"> <xpath>/Defs/FactionDef[@Name="VFEM_MedievalFactionBase"]/modExtensions</xpath>
<value>
<li Class="VFECore.FactionDefExtension">
<siegeParameterSet>VFEM_Medieval</siegeParameterSet>
</li>
</value>
</li>

I have already suggested it in the comment, you may modify the file yourself before Oskar come up with a new fix.

That did not fix it for me.

I was able to get the Medieval Factions to spawn with Catapults, with only VE Framework, VFE: Medieval and VE: Security and no other mods. The issue for me is they huck two stones and assault, making the siege rather pointless.

EDIT: Issue with the second siege I used Dev Mode to spawn ran into an issue of dropping down an every increasing number of chunks (the ammo for the catapult) as the pawns who came could not move them away from the catapult blueprint to build it, which I assume is the trigger for the chunks to stop pawning.