I can see a few issues here for sure.
As already noted this tank is way deep. This will pose problems with just about every aspect of growing plants if not addressed. Obviously lighting could be too low but also I'd look at your flow too. You have what looks to be a fluval canister filter. What model number and how many litres is this tank. If flow is poor you may have issues getting co2
, oxygen and other nutrients to the plants although with root tabs deployed nutrients might not be too bad.
The main issue here I think is the type of fish you have. They could easily be feasting on those plants, especially if they are suffering to begin with.
Fish type and lack of water changes may also increase dissolved organic compounds. As the plants decay, ammonia is released and oxygen is consumed. This promotes algae and if dissolved organics compounds are high enough this will affect plants too.
If you switch the filter off do you get a oily film on the surface at all? This will also reduce light which may not be adequate enough already.
There's a few things you can do to improve this tank but I feel that with hungry angel fish and plecos the plants are already at a disadvantage.