There is only one interaction of Matt to MC on each path... In Lover, he will only text you because Liz did not come to work and that's it. In Happy andNTR path, you eventually go to a resto where Matt and Liz are hanging out. Matt will then text you to distract you while Liz is under the table, giving BJ to Matt.
If you are still in v21.3 or lower, those pics are bug. You need to update to 21.4 for the bugfix.
Once done, you can go back and run the dialogues again below:
L226 - NTR route. Go back to the dialogue where Liz invites you to a cafe wearing the red top. The pic is one of the comic clip (Note: NTR only, not NTR-NTS).
L236 L238 - Lover path. Go back to the dialogue for the 2nd visit to Liz lunch. The pics are on that comic clip.
IMPORTANT: Accessing the comic clips from the gallery is not enough. You need to run the whole chat conversation for those comic clips instead.