"Maps to" to execute signal trade pairs with _SB suffix ?

[TheCustomer]

I've set up MT5 & signal (follow), and linked the account to my broker

So far, so good.

& I've set up accounts before, so I don't think I've done anything different to break the setup.

What's new is that I'm running from a Broker's spread betting account, so Pair symbols are all suffixed _SB   ... GBPJPY_SB etc

I've created custom symbols to match the signal's pairs, without _SB ,  which I thought would allow trades to execute

But so far, trades aren't executing.

I get this error message

2021.05.20 07:41:03.455 Signal '52006390': deal #120217224 buy 0.15 XAUUSD at 1874.98 skipped as no symbol found

Do I also need to map the broker's _SB symbol to the custom pair,?

& if so, how do I do that?

(the manual shows no search results for mapping)

tia

[TheCustomer]

TheCustomer:

I've set up MT5 & signal (follow), and linked the account to my broker

So far, so good.

& I've set up accounts before, so I don't think I've done anything different to break the setup.

What's new is that I'm running from a Broker's spread betting account, so Pair symbols are all suffixed _SB   ... GBPJPY_SB etc

I've created custom symbols to match the signal's pairs, without _SB ,  which I thought would allow trades to execute

But so far, trades aren't executing.

I get this error message

2021.05.20 07:41:03.455 Signal '52006390': deal #120217224 buy 0.15 XAUUSD at 1874.98 skipped as no symbol found

Do I also need to map the broker's _SB symbol to the custom pair,?

& if so, how do I do that?

(the manual shows no search results for mapping)

tia

there's a short thread here from 2019 which suggests the system searches pairs on the first 6 characters, and attempts to match them.
So a _SB suffix shouldn't affect that. 
If that's how things worked in 2019, is it still the case?

& if so, what am I missing that's stopping trades?!

https://www.mql5.com/en/forum/311109?utm_campaign=search&utm_medium=special&utm_source=mt5terminal

[TheCustomer]

per https://www.mql5.com/en/users/newdigital 's suggestion in that thread I've added both the pair and the pair_SB to Market watch

So far the Market Watch pair_SB is working: the pair (no _SB) is greyed out and inactive

:-/