Mallus Maccius No Longer a Fence

I began a new character with patch 1.4.21.4

I completed the Thieves Guild story line, where Mallus Maccius pledges to me to be a fence for my services. I moved on and became the Guild Master.

Now I am on a side quest to get to "Return the lexicon to Avanchnzel". So I decided to dump some of my gear. But to my surprise, with Mallus there are no dialogue options for a transaction. He says I have developed the brewery by dumping the last of the Honning-Brew mead. But no options for selling.

Before this patch, another character that I played, I was able to fence/sell my stuff just fine with Mallus.

Now I can not.

So far I have been following G.SE on how to avoid known glitches altogether.

If other people have experienced this problem, does some one know how to avoid this glitch for Mallus Maccius?

EDIT

Neither is Niranye in Windhelm, who should be a fence once you complete the Thieves Guild quest line as well.

At this point I think it is one and only one mod that I have active. When I started this play through with the latest patch (no longer latest since 1.4.27 I think) I had never used a mod. Only subscribed to one on Steam "Dovahkiin Hideout" for the big house, more space etc.

Maybe this is why my usual fences might not be fences. But Golum-Ei still is a fence. Too confused at this point.

Anyone in the gaming community have any problems with this particular mod?

Mallus Maccius not being available as a fence is a known bug.
According to UESP:

Mallus Maccius may not have the option to sell merchandise after completing Dampened Spirits, despite offering to provide fence services to you. Instead, at odd hours of the day, he will respond as if the player is disallowed from entering the building.
A possible fix for this is entering the Meadery through the basement.

Of Niranye a similar bug is not registered on UESP.
It does state on elderscrolls.fandom.com, however, that the mission Summerset Shadows must have been completed (which is not a necessity for completing the main Thieves Guild questline), and that she mustn't have "fought" (turned hostile towards the player, I presume) in the process.

Since, according to its description, it only "adds a very large basement connecting all houses in the game", it is unlikely that Dovahkiin Hideout has influenced the fences in Skyrim. Nothing about it is mentioned in the mod's thread on the nexus.