Alright, I posted a part of this earlier. I hope that this is the right place. I heard somewhere that I should come here for problems regarding TS rather than at the Black Wyrm, if that's incorrect then I'll repost it there.
Okay, I had Kachiko and Yoshimo in my party but I didn't want Kachiko. So, I let her open up a cell in the Copper Coronet and her close herself in it. Then I kicked her out of the party. For awhile I could not save in that place. However several quests later I could save in the Copper Coronet and went back to see where Kachiko should be and she was Gone!!
Now, I never saved Jaheira but after I found out that Kachiko was gone, I went to the Sea Bounty Tavern and found Baron Ployer there! Now, I know that this place is Kachiko and Yoshimo's normal go-to place if they've been kicked out. Any chance of a connection here?
Also, I have Valygar in my party but I cannot open the Planar Sphere. Do you have to be in Chapter 6 for this to work? I cannot remember. If you could help, it would be great 
big bad nasty diamond, but very good at modding and fixing stuff so we let him off this once. okay as i'm passing through will try to lend a hand.
locking Kachiko up is never gonna work, she'll just drift off through the wall like a ghost on route to her next global.
there are a few posts about kachiko being kicked out etc. worth a trawl through old posts for solutions on bringing back the stroppy cow.
you do not have to be in chapter 6 to do planar sphere, but not advisable to attempt this in chapter 2 either as there are golems, beholders, liches and high level mages. it can be done in chapter 3 but not for the faint hearted and i diverse, slightly. anyway, Valygar in party and no PS entry is def. a global not quite right somewhere. Clua'ing inside would work but i think your still missing a trigger, i'll dig around for conditions and pm you, providing you know what
IE or
SK is, right??