On the MP Compact MKIII and Nova MK II the "!S1<CR><LF>" status command is processed immediately (during batch printing). However, on the MP Compact MKII & Nova (Firmware 5.5.29) the printer is waiting until a print job is processed and than an answer on the !S1 status command is given.
Printers Hardware: MP Series
To get this issue resolved it is required to use firmware APP_MPCompact_15.04_0165_S8571 or higher. The printer will wait until a print job is processed and than an answer on the !S1 status command is given. This is the same functionality like on the MP Compact MKII & Nova printers.