I have 400 specific orders open at all times, but alpaca shows fewer than 200, depending on how many other (independent) orders filled in the mean time. I’m guessing the bug is caused by the limit of open orders that the web frontend uses to poll. The current API limit for queried orders (500) is way too restrictive for my purposes. I worked around it by storing all trade orders in a local database, but that is a real pain to sync if the connection is dropped. Either way, the web frontend should not suffer from this bug – it should always show /all/ open orders.
Please let me know if I can provide any further information.