Why don't dicarboxylic acids show hydrogen bonding in spite of the fact that carboxylic acids exist usually as dimers in polar aprotic solvent? I have seen several examples:

The fact that maleic acid is more soluble in water than fumaric acid in spite of the fact that it must be able to show intramolecular hydrogen bonding.
trans-Cyclopentane-1,2-dicarboxylic acid is more stable than the cis form (cis form should be able to show hydrogen bonding).
o-Nitrobenzoic acid is more acidic than the para isomer.

I tried linking point 1 to acidic strength (maleic acid &gt; fumaric acid because of hydrogen bonding in conjugate base) and point 3 to acidic strength (o-nitrophenol &lt; p-nitrophenol)
What am I missing? Something related to the size of the ring?
I would like to object the statement dicarboxylic acids would not engage hydrogen bonding.  Terephthalic acids ($\ce{HO2C-C6H4-CO2H}$) are a prominent example since early attempts to formalize the description of intra- and intermolecular hydrogen bonding in the solid state. Consider the pairing of benzoïc acid and $p$-terephthalic acid, sharing the same motif of hydrogen donors and acceptors, described as $R_2^2(8)$ in Etter's notation:

(Etter, Acc. Chem. Res. 1990, 23, 120-126,  doi 10.1021/ar00172a005)
But there is no limit to $p$-substitution to find this motif again, e.g.:

(Holy et al., Collect. Czech. Chem. Commun. 2006, 71, 139-154, doi 10.1135/cccc20060139, researchgate.net)