Makes sense, seems like no default is defined anymore, so it won’t render without using a style.
I use apa, and the attached screenshot shows my problem.

\startbuffer[testbib]
@Article{testone,
  author={Testperson, A. B.},
  title={Thing with one author},
  year={2001},
}
@Article{testtwo,
  author={Testperson, A. B. and Friendperson, C.},
  title={Thing with two authors},
  year={2002},
}
@Article{testmany,
  author={Ah and Bee and Cee and Dee and Ee and Eff and Gee},
  title={Thing with two authors},
  year={2002},
}
\stopbuffer

\definebtxdataset[main]
\usebtxdataset[main][testbib.buffer]
\setupbtx[dataset=main] % make cite use this
\setupbtx[default:cite][alternative=authoryear] % cite style
\usebtxdefinitions[apa] % load and activate list rendering
\definebtxrendering[main][apa][dataset=main, pagestate=start]

\starttext
\cite[authoryear][testone] \cite[authoryear][testtwo] \cite[authoryear][testmany]

\cite[authoryears][testone] \cite[authoryears][testtwo] \cite[authoryears][testmany]

\subject{bib}

\placebtxrendering[main][method=global]
\stoptext


Am Mi., 19. Feb. 2020 um 16:35 Uhr schrieb Thomas A. Schmitz <thomas.schmitz@uni-bonn.de>:
It is difficult to answer your question because we don't know which
specifications you use for your citations. You will have to provide a
minimal example that allows us to see what you're doing.

Thomas

On 2/17/20 6:26 PM, Philipp A. wrote:
> Hi List,
>
> I want the comma gone from “et al.” citations, and modify the cite
> alternatives:
>
>   * [authoryear]: (Surname, et al., 2018) → (Surname et al., 2018)
>   * [authoryears]: Surname, et al. (2018) → Surname et al. (2018)
>
> Also I’d like to configure how many names are the maximum before all
> except the first are replaced by “et al.”
> i.e. \setupcitething[maxauthors=3]: (One, Two, Three, & Four, 2018) →
> (One et al., 2018)
>
> How can I do this? I didn’t find anything in the publications manual:
> http://pragma-ade.nl/general/manuals/mkiv-publications.pdf
>
> Best, Philipp
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