1) If there is an item soulbound to your account, you should always be able to see it in the market. For example you go on an expedition and you get a drop 10 levels higher than your level. Someone from your guild asks for a gold packet, without checking you place that item into the guild market, he buys it, he places it back in market and you neither can see it to buy it nor can take your item back in any way.
2) you should be always able to take soulbound items to your account from the guild warehouse, even if someone else has placed it there. For whatever reason, your item ended up in someone's else hands (as in example 1) and he placed it in warehouse for you to pick it back again but you cant due to the level restrictions