Small value capacitors are difficult to measure. 1nF could be "out of range" for your tester (see the user manual for it). As long as they don't measure a short circuit, they can't kill anything. In fact, I measure resistance instead. So with DMM highest resistance range, check it reads O/L. A capacitor must not pass DC current.
They don't often fail or have a very wrong value and since difficult to measure, we would swap them out if there was a reason to suspect them.
On the DAC output, you have a low-pass filter something like the one top right here. The input comes in at R1 and note there is only a connection "dot" instead of a capacitor.
For the other High-pass example, there is an input capacitor C1, but it has a resistor R2 from +input to 0v. R2 is "referencing this filter to 0v. As it happens, both C1 and R2 are essential parts of this filter circuit while the Low Pass is the opposite and so has no referencing resistor.
Now see the Band Pass filter made by adding the two in series. There is no coupling cap between them because the low pass filter needs DC reference at 0v and it gets this from the preceding stage which is in turn, referenced to 0v by that resistor to 0v.
Note that individual circuit tutorials frequently leave out any mention of what it requires before and after it since it isn't directly relevant to what they are teaching. You do need to know that the +input of an opamp, must have a resistive connection (that can be 0 ohms for inverting circuits) coming from somewhere.
So, in the DAC filter you have, the referencing can be done at the input resistor directly after the input capacitor. Fit a resistor from there to 0v. The resistor can be at least x10 the value of the input resistor.
Note, interestingly, you won't find this "no reference" fault by checking voltage on the opamp pins. Your meter has an input resistance (1M to 20M depending) and with the black probe on 0v, the meter will itself reference the circuit to 0v when you connect the red probe.