The merge of duplicated entries lead to destruction of entry's data structure

[TerenceWSK]

The screening options are "matching keys" and "matching DOI". The merge method is "combine". 2 out of 3 pairs of duplication have this issue. Here is an example

Before merge (entry * 2):

@article{Jiang2018,
author = {Jiang, Xiantao and Lu, Huiling and Li, Qian and Zhou, Hang and Zhang, Shengdong and Zhang, Han},
doi = {10.1515/nanoph-2018-0102},
issn = {2192-8614},
journal = {Nanophotonics},
month = {oct},
number = {11},
pages = {1835--1843},
title = {{Epsilon-near-zero medium for optical switches in a monolithic waveguide chip at 1.9 $\mu$m}},
volume = {7},
year = {2018}
}

After merge:

@article{Jiang2018,
    title        = {{Epsilon-near-zero medium for optical switches in a monolithic waveguide chip at 1.9 $\mu$m}}
}
}
}
}
}

[TerenceWSK]

Later, I discovered that occasionally non-duplicate entries got destroyed the same way. My bib has 297 entries, I do not know if this is related to the number of entries in a file (too many?)