Online Contributions sometimes not creating a CSI

Online contributions come through on account and generate a CSI. Every now and then (like, once a year maybe), a contribution comes through without a CSI. I think it tends to be when coming through contribute1, not ticket order add-ons. Using TNEW v7, Tessitura v15.

I have two contributions that came through yesterday, one created a CSI, the other didn't. I've checked and re-checked that the fund options listed are connected to CSIs in LTR_TNEW_CUSTOM_FORM_SAVE_DATA. I haven't touched this table in months, so I can't imagine it's a caching issue.

When checking the site logs for both contributions yesterday (and a little testing this morning), I consistently see the following message:
Info | Contributions | Contribution Group Page slug value (contribute1) not found for contribution type (#0)+|[buncha numbers; different each time]

Anyone have experience with the CSI issue, or the message above? I see the message for contributions that successfully create CSIs, so not sure if there's correlation here.