Weird ULN2003 to 7-segment behaviour in Proteus
The circuit you show will work fine in reality (assuming that you also add the resistors in series with the display to limit the current).

In proteus it doesn't behave as expected, the open collector outputs of ULN2003 are not pulled high through the LED as they are supposed to be, this is a simulation model misbehavior.

The solution you can use it to add pull up resistors (I have used a resistor network) like shown below:



The shown schematic is valid for simulation only, the pullup network is not needed in the real circuit. You also have to add the series resistors to the segment lines which are omitted in proteus to improve the simulation speed.