Golay error correction was introduced in 2019.4. The suggestions in your error message encourage you to work with reverse-complementing parameters, because orientation matters when you're using error correction. This has been discussed a number of times on this forum - here's one example.
A colleague of mine was successful in demultiplexing your test data with error correction using the following:
qiime demux emp-paired \
--i-seqs mux.qza \
--m-barcodes-file test_metadata.txt \
--m-barcodes-column Golay_Barcode \
--p-rev-comp-barcodes \
--p-rev-comp-mapping-barcodes \
--o-per-sample-sequences demux.qza \
--o-error-correction-details ecc.qza \
--verbose
Try something similar with your complete data set, and let us know how it goes for you. As a side note, it's also possible to turn golay error correction off using --p-no-golay-error-correction. This will likely lose you some reads, save you some time, and give you similar results to what you got in 2019.1.
Best,
CK