Did you have "real-time" quotes on your papertrading system? usually they only have delayed quotes which is about 10-15 minutes if you are just using an unfunded paper account. When you fund your account you may have to ask them to make sure your paper TOS version is real-time.
Personally, I've found that with the real-time quotes TOS simulates the limit orders fairly well, at least better than it used to be pre-TDAmeritrade acquisition original TOS platform. (Fortunately after the TDA acquisition, the improvement of the platform has been prioritized, so marked improvements are constant; when prior , promised improvements would develop at a snail like pace) It's not exactly perfect to live options trading, but it's fairly close now, so yes it does simulate the frustrating non-fills of options of a multi-legged spread not able to be sold or bought back.
If you want to hear my "unwanted" option, the CBOE pits is still a market-maker ripoff machine, meaning what you see on paper or even your own estimates with option prices, one is very likely having to give those locals(if not replaced by market making computer algos now; it's still the same as those algo bid-askers will still pinch the retailer) a tithe for each leg you see of a spread. Some of the former pit market makers actually sell courses and mentorships and such trying to get you to trade what "used to" (or maybe never did ) work in the form of risky delta-neutral spreads such as calendars and iron condors. so, yes, one can use cboe.com's free videos and information for free learning, but as always to learn any directional or non-directional elusive edge, it's not going to be just shared for free; or up to the individual to find their own way.
As an update, I now have an account open with Options House. Their platform is a bit primitive and confusing compared to TOS, but at least they tolerate an Australian.
Still not ready to commit real cash to a system, I experimented yesterday with a virtual market order, hoping that the system would get me in at the mid point. Not so.
Before the open, the bid ask spread were
1.65 and 3.60
1.95 and 3.00.
My BTO orders got virtually filled at - guess what? yes, the ask price.
It's a challenge.
The next hurdle is trying to trade live with only $700 cash in my account.
According to FINRA/OH, I need $2K cash in the account before I can open a spread.
I have yet to discover what their definition of a spread is.