I don't know if these theories have been brought up, but it looks like a few things were happening around the beginning of 2018.
One of them was the meeting in Parliament of We Need to Talk UK on the 14th of March.
I am speculating, but it is possible that Jess decided to focus on countering feminists more than keeping the focus on ATH.
According to NUS officer Miles Fleet:
When the committee was formed, I was pretty keen to work on housing-related policy, and later in the year asked Jess why housing seemed to have taken a back seat in our campaign. She explained it was because working on the Gender Recognition Act reforms (which we didn’t know were happening at trans conference last year) and our response to it, were more urgent, and was something I entirely understood, as trans activism I had been doing in London was currently focused on that too.
Another point to note is there was a whole bunch of NUS drama in January/February when the leader, Shakira Martin, was accused of bullying. There seems to be little love lost between Shakira (who was subsequently re-elected to the presidency) and Jess.
Jess is on record saying:
Another statement posted on Twitter by Jess Bradley, trans students officer at the NUS, contained some allegations about Martin’s behaviour. Bradley said: "I think they show just how difficult it is to talk to her directly, privately or through proper channels, even about relatively minor concerns".
Bradley said her working relationship with Martin was untenable and had "created a situation where NUS culture is pretty broken".
www.thirdsector.co.uk/national-union-students-tells-officers-work-home-bullying-allegations-probed/management/article/1456045
A third point:
Remember that poster who advertised extra security services to transfeminine people in the media? They go by the name Ada Cable on Twitter.
Interestingly, someone named Ada Cable has been co-opted as a trans officer for the NUS, but isn't really mentioned on the main web-page itself.
Co-opted Member - Ada Cable
Since being co-opted to trans committee in September, I’ve been working to hold Jess accountable mainly by providing additional trans women's voices on the committee and ensuring that multiple perspectives are listened to.
I've pushed for trans women to be included in nus events and extended invitations to jess and other NUS reps to speak at events organised by other groups.
My activism within the NUS has largely consisted of organising with the NUS and other groups, including the work UK trans info is doing running trans security trainings for vulnerable trans people, and using the training provided by NUS trans and ARAF campaigns to begin work on street first aid groups in London.
We’ve also begun work with several other organisations on building a community care syllabus, to better equip activists to do more rigorous care, support and advocacy in the trans and queer communities.
Outside of the NUS I’ve carried out intense advocacy, as well as frequent speaking, training and organising engagements, as well as continued writing on the subjects of transfeminism and prison abolition.
From the accountability page:
www.nusconnect.org.uk/conferences/trans-students/accountability
The other thing that might be worth bringing up is that Ada Cable was involved in the Twitter storm after the Hyde Park attack. She was tweeting support for the attacker, although it looks like these have been deleted. Screenshots live on in feminist pages, though, including Skepticat UK's blog.