I believe there are only four instances of τὰ Συμβεβηκότα in Diogenes Laertius book 10, all in the letter to Herodotus.
10.40b [Sedley] Over and above these [atoms and void] nothing can be conceived, either by imagination or by analogy with what can be imagined, as things grasped in terms of complete natures, and not as what we call the "accidents " and "properties (συμβεβηκότα)"of these.
10.50b [Hicks] And whatever presentation we derive by direct contact, whether it be with the mind or with the sense-organs, be it shape that is presented or other properties (συμβεβηκότων), this shape as presented is the shape of the solid thing, and it is due either to a close coherence of the image as a whole or to a mere remnant of its parts.
10.68b [Hicks] Moreover, shapes and colours, magnitudes and weights, and in short all those qualities which are predicated of body, in so far as they are perpetual properties (συμβεβηκότα) either of all bodies or of visible bodies, are knowable by sensation of these very properties – these, I say, must not be supposed to exist independently by themselves (for that is inconceivable).
10.71b [Hicks] Nor, on the other hand, must we suppose the accident to have independent existence, for this is just as inconceivable in the case of accidents as in that of the permanent properties (τῶν ἀίδιον συμβεβηκότων); but, as is manifest, they should all be regarded as accidents, not as permanent concomitants, of bodies, nor yet as having the rank of independent existence. Rather they are seen to be exactly as and what sensation itself makes them individually claim to be.
We also have this, which is probably from Epicurus' book 25 On Nature:
P.Herc. 419 fr. 5: …οὔτε γὰρ ἕν̣ [τί] [ἦν] ὧς τὸ συμβεβηκ[ὸς] [κ]α̣ὶ ὧι συμβέβηκ[ε] [ῥη]τέον εἶναι – οὔτ[ε ἕτε]ρον ὡς τὸ ἀ[πό τινος δι]αστήματος [ἐπεισερχό]μενον…
Therefore we know that:
The whole natures are, and are only, the atoms and the void. Everything is either an atom or the void – or an emergent characteristic of atoms and void. Emergent characteristics are of two types:
(1) Lucretius gives examples of inseparable characteristics (τὰ Συμβεβηκότα): Weight to stone, Heat to fire, Liquidity to water, Touch to bodies.
(2) Lucretius gives examples of separable characteristics (τὰ Συμπτώματα): Slavery/Freedom, Poverty/Riches, Peace/War.
---------------
There is more in Philodemus, but I am not sure where LSJ is getting the idea that τὰ Συμβεβηκότα "do not feature in the definition" of a thing. I would have a hard time "defining" fire without mentioning heat, and the same for the rest of Lucretius' examples.