@Jimbo96 a quick primer on bass management. There are two components to bass in an AVR. Bass that is part of the main channels and the Low Frequency Effects (LFE) channel. LFE content is found in movies and it is the .1 that is part of 5.1 surround tracks. There are two crossover settings in most AVRs. A subwoofer crossover and the LFE setting. Since the LFE content gets routed to the subwoofer output on the AVR, the LFE settings is typically set at the max of 120Hz so as not to cut off any LFE content.
The subwoofer settings come into play with the rest of the bass content. In your AVR speaker setup If the subwoofer is disabled the speakers get a full range signal. With the subwoofer enabled, content below the crossover frequency will get routed to the subwoofer. A typical value for the crossover is 80Hz but can be adjusted to suit the speakers and room. Note that when the subwoofer out on the AVR is used the crossover setting on the subwoofer plate amp is set to max so as not to conflict with the AVR crossover setting (the plate amp control is used when passing a full range signal to the subwoofer).
What gets confusing for some is the speaker size setting and subwoofer mode setting on the AVR. If the subwoofer mode is LFE only, then only the LFE track gets routed to the subwoofer output. To get both LFE and bass content, the mode is set to "LFE + Main" (this is for Denon and other makes may use different wording). So if you play 2 channel music and the subwoofer mode is set to LFE, you will not get any bass content sent to the subwoofer output. LFE + Main is the setting normally used.
Setting the speakers to large or small determines where the bass content goes. If all speakers are set to small then all bass content goes to the subwoofer only. If the speakers are set to large, bass content gets sent to both the subwoofer and the large speakers. For example, if you had full range towers for your L+R, you could set them to large and set all other speakers to small. It is common to set all speakers to small and let the subwoofer handle the lower frequencies as few people have true full range towers. Some people will set the L+R to large to get added mid-bass. That's a personal choice. Some AVRs use different terms for this like "double bass" on Onkyo AVRs.
So you can see that it's possible not to get any bass signal to your subwoofer if the AVR settings are incorrect.