Yes, this exactly. We went into offline mode 1st and then that stopped working completely (all cards/taps payments rejected). So we asked every customer if they had cash before taking their order and we're able to complete those transactions just fine.
Soon afterwards, both of our terminals (iPad) were kicked out of the app and we resorted to paper and calculator for cash only.
So, if you are logged in already you can use offline mode.
If you use their point of sale software to track cash sales and are not logged in already, your pretty screwed at this point.