I am pasting the first part of that reference directly taken from the RIS file. It seems like Zotero is using the first "M1 - " line to populate the issue section.

TY - JOUR
M3 - Article
Y1 - 2024
VL - 30
SN - 2352-3441
JF - Arthroplasty Today
JO - Arthroplast. Today
UR - https://www.embase.com/search/results?subaction=viewrecord&id=L2035001264&from=export
U2 - L2035001264
DB - Embase
U3 - 2024-10-15
U4 - 2024-10-17
L2 - http://dx.doi.org/10.1016/j.artd.2024.101496
DO - 10.1016/j.artd.2024.101496
LK - https://www.rightfind.com/vlib/order/OpenUrlReceive.aspx?ClientID=11745?sid=EMBASE&sid=EMBASE&issn=23523441&id=doi:10.1016/j.artd.2024.101496&atitle=Conversion+of+Unicompartmental+Knee+Arthroplasty+to+Total+Knee+Arthroplasty+for+Cement+Allergy&stitle=Arthroplast.+Today&title=Arthroplasty+Today&volume=30&issue=&spage=&epage=&aulast=Edelstein&aufirst=Alexander&auinit=A.&aufull=Edelstein+A.&coden=&isbn=&pages=-&date=2024&auinit1=A&auinitm=
A1 - Edelstein, A.
A1 - Lachance, A.
A1 - Cush, C.
A1 - Lutton, J.
M1 - (Edelstein A., Alexanderi.edelstein@guthrie.org; Lachance A.; Lutton J.) Department of Orthopaedic Surgery, Guthrie Robert Packer Hospital, Sayre, PA, United States
M1 - (Cush C.) Lewis Katz School of Medicine, Temple University, St. Luke's University Health Network, Bethlehem, PA, United States
AD - A. Edelstein, Department of Orthopaedic Surgery, Guthrie Robert Packer Hospital, 1 Guthrie Square, Sayre, PA, United States
T1 - Conversion of Unicompartmental Knee Arthroplasty to Total Knee Arthroplasty for Cement Allergy
LA - English
KW - cementless prosthesis
... Continues...

In contrast, for other references which include an explicit "IS -" line, this is the value used for the issue field, as expected, such as the value "18" in the following example (from the same RIS file):

TY - JOUR
M3 - Article
Y1 - 2025
VL - 14
IS - 18
SN - 2077-0383
JF - Journal of Clinical Medicine
JO - J. Clin. Med.
UR - https://www.embase.com/search/results?subaction=viewrecord&id=L2036291727&from=export
U2 - L2036291727
DB - Embase
U3 - 2025-09-30
U4 - 2025-10-08
L2 - http://dx.doi.org/10.3390/jcm14186558
DO - 10.3390/jcm14186558
LK - https://www.rightfind.com/vlib/order/OpenUrlReceive.aspx?ClientID=11745?sid=EMBASE&sid=EMBASE&issn=20770383&id=doi:10.3390/jcm14186558&atitle=Comparison+of+Fracture+Resistance+Using+Two+Different+Major+Cemented+Stems+in+Osteoporotic+Bone+Models&stitle=J.+Clin.+Med.&title=Journal+of+Clinical+Medicine&volume=14&issue=18&spage=&epage=&aulast=Hashimoto&aufirst=Kohei&auinit=K.&aufull=Hashimoto+K.&coden=&isbn=&pages=-&date=2025&auinit1=K&auinitm=
A1 - Hashimoto, K.
A1 - Nakamura, Y.
A1 - Takahashi, N.
A1 - Morishima, T.
M1 - (Hashimoto K., skikohei4145@gmail.com; Nakamura Y., yxn14@aol.jp; Takahashi N., ntakahashi0617@aichi-med-u.ac.jp; Morishima T., takkan@aichi-med-u.ac.jp) Department of Orthopedic Surgery, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Japan
M1 - (Nakamura Y., yxn14@aol.jp) Department of Orthopedic Surgery, Division of Osteoporosis, Locomotive Syndrome, Joint Disease Center, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Japan
AD - Y. Nakamura, Department of Orthopedic Surgery, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Japan
AD - T. Morishima, Department of Orthopedic Surgery, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Japan
T1 - Comparison of Fracture Resistance Using Two Different Major Cemented Stems in Osteoporotic Bone Models
LA - English
KW - AMIS-K 4S3
...Continues...

The behavior is systematic. The RIS file contains a few references that do not include the "IS -" line and in all cases Zotero is using the first "IM -" line as Issue. This happens with different RIS files and since the error happens during the import process it affects any citation style that I use later.

In case it is relevant, I am currently importing the RIS files using:
File -> Import... -> A file (BibTeX, RIS...)

Hope this helps, thank you!