PC [BUG] Mailbox glitch after Willy's 100 juicy bug quest

[SCB]

I completed the Juicy Bug quest, and the next day there is as expected mail from Willy. Only upon clicking the mailbox the mail icon disappears and no letter opens. When I go to my read mail, it shows an empty letter with "-Willy" in it. I assume this letter is supposed to carry an item and some words of thanks, as the other quests have had. No other issues, but I'd hate to miss out on whatever was in that letter.

I'm on Winter 28, year 1. No other mail. Previous mail was Gus' Albacore quest on the 26th.

Single player, running latest version of Stardew via Steam on PC. I only run SVE and the supporting mods required to run it, all up to date. SMAPI is showing no errors.

EDIT: It seems the letter is of no consequence, he offers his reward during a cut-scene at the beach. So it's a non-issue issue.. probably a loose end that needs tying up. Either the letter will tell you to come to the beach or it'll be removed completely.

 

[KonaKona]

Having similar issue with Demetrius' fishing quest. After completion I have a mail indicator on the mailbox, but when opening it, nothing happens and the indicator disappears. This has made it impossible to receive the enclosed crafting recipe, and I still receive the same empty mail indicator every day.

Strangely, a friend joined my game in co-op and got the mail and recipe immediately.

EDIT: After inspecting my save file, I noticed it says <mailbox><string>LeoCooking</string></mailbox>, and this remains there every day after saving as well.
Seems this is another mail bug and I'm unable to receive the cooking recipe from Leo either.

EDIT2: I was able to fix the LeoCooking mail bug by editing my save file and manually adding the recipe to my list, and now I no longer receive the empty mail notifications. I still am not able to get the Demetrius crafting recipe though.

EDIT3: Solved I think.
I believe I accidentally put an old mail.xnb personal mod from 1.4 and overwrote the 1.5 mail.xnb, resulting in the blank mails coming in as those letters don't exist.

 

[TheFireNight]

I have the same kind of issue with the mod "more quests". The mailbox shows an awaiting mail for 2/3 days, until I finally can obtain it.
I though it was an issue with that mod.